chronicles-of-darkness-1eedition-comparisonworld-of-darkness
In some answers I saw in the last year that were focussing on the Storyteller system of WoD, someone answered with the Storytelling system of the CoD in mind, usually noticeable by referencing to the wrong game or outright calling it out.
What are the main mechanical differences between the two game lines?
This is not about:
If I understand correctly, you need at least one d10 to get 8 or more to succeed, yes? And you get more dice if you have more ranks/skill level/whatever, right?
In that case, the other answers are correct, but I'd also like to have a go at explaining this:
Assuming a uniform distribution (meaning, all results are equally likely), reasoning with dice is pretty simple: To calculate the probability of an event, you just count the number of possible results that make the event true and divide it by the number of possible results. So, in our case the possible number of results is 10. The event of success has 3 results (8, 9, 10) and the event of failure has 7 results (1, 2, 3, 4, 5, 6, 7). So the probability of succeeding with one die is \$\frac{3}{10} = 0.3\$ and the probability of failing is \$\frac{7}{10} = 0.7\$.
To calculate the probability of independent events (like rolling normal dice which can't interact with each other), you just multiply the probability of the event occurring once with itself as many times as the event repeats. To extend the previous example, the probability of failing once is 0.7, the probability of failing twice is \$ 0.7 \times 0.7 = 0.7^2 \$, the probability of failing thrice is \$ 0.7 \times 0.7 \times 0.7 = 0.7^3 \$ and so on.
Now, if two events cover the whole spectrum of possibilities, then the sum of their probabilities is 1. For example, the events "failing three times with three rolls" and "getting at least one success with three rolls" are complementary. So, the probability of getting at least one success plus the probability of getting three failures is 1. Solving this trivial equation, you get that the probability of succeeding at least once with three rolls is \$1-0.7^3\$.
Here's a chart that does this same work for any number of dice from 1 to 10.
To make this a bit more general, the probability of getting less than X with one Y-sided die is is \$\frac{X-1}{Y}\$. So, the probability of getting less than \$X\$ with \$N~Y\$-sided dice is \$\left(\frac{X-1}{Y}\right)^N\$. The probability of getting at least one \$X\$ or higher after rolling \$N~Y\$-sided dice is \$1 - \left(\frac{X-1}{Y}\right)^N\$. It should all make sense now, hopefully.
There is a built in limit to how many ghouls a vampire can have - their blood. Ghouls require upkeep in the form of blood, at least once a month and any time the ghoul needs to heal (if the vampire cares about helping the ghoul heal). They also need blood to power their own disciplines, should they have any, or boost their stats.
The simple fact that a vampire has to hunt much more to support more than a single ghoul is a natural limit to the number of ghouls they can have.
Now for your Ventrue feeding off his own ghoul before feeding the ghoul its monthly dose - the books even advise using that against the players. Ghouls of the Camarilla are known to the court and are quite often tampered with by other kindred. Feed the ghoul blood from another kindred, and have the Ventrue in question get blood bound to the other kindred. That behavior will end quickly... or not, the player character would be blood bound, so they might continue.
Additionally, Ventrue's weakness is well known. Kindred of the city might very well try to determine the character's herd based on what they know of the ghoul, there by cutting the Ventrue's food supply off in the city.
In the situation you are describing, the Ventrue is telegraphing to everyone how to hurt him by taking a ghoul he can feed off of, let alone actually feeding off of them. Let the natural consequences of that decision play out.
There is an additional check you can invoke if the prince of the city is not counted amongst your players - your players do not have the right of creation. The traditions explicitly restrict the right to create kindred to the prince of the city, but the creation of others of the blood is usually interpreted to include ghouls. It is the prince's prerogative to simply have excess ghouls killed off, strip status from the offending kindred, or even go so far as issue a blood hunt for a rampant ghoul creator.
Your main solutions in this situation are political; the books imply that this is one of the intended checks and balances against mass ghouling. Of course, this goes out the window in a Sabbat game, where you are supposed to create ghoul and neonate armies as a matter of course.
Best Answer
Fixed Target Number on Dice
Storyteller uses variable Difficulties (target numbers) that vary by circumstances.
In Storytelling, the target number you need to roll for a die to be counted as a success is fixed at 8, and any situational modifiers are applied to the total number of dice you roll (your "die pool").
Botches
In Storyteller, a botch is defined as rolling at least one 1, and either zero successes, or fewer successes than 1's, thus giving a possibility of a botch on any roll.
In Storytelling, a botch is only possible when rolling a Chance Die (when your pool has been penalised into the ground).
In the second edition of Chronicles of Darkness, (still called Storytelling just to maximize confusion) Dramatic Failures are available whenever you fail a Chance Die or whenever you simply fail a roll and you agree to take a DF in return for a fraction of an XP (a "Beat").
Different Attributes
Storytelling tried to shift to a more uniform 3×3 matrix of attributes, cross-referencing power, finesse and resiliance against the physical, social and mental. Some attributes differ drastically as a result. Also, how some derivative characteristics are calculated or even what they are differs.
Willpower Uses
In Storyteller, using WP gives automatic successes.
In Storytelling, it provides bonus dice. Also, how the base Willpower rating is calculated or purchased varies.
Different Virtues
Virtues in Storyteller are primarily a VtM thing, and are ratings.
In Storytelling, a Virtue and a Vice are more like Archetypes which you choose from a list. They provide some game-mechanical effects for when you recover Willpower.
Distinct vs. Unified Attack/Damage Rolls
In Storyteller, you roll to hit, the enemy rolls to dodge/parry/block, then if you hit you roll damage and the enemy rolls soak.
In Storytelling, the attack/damage roll is a unified thing, and the unified defence value is subtracted from the attack; attacks are resolved in a single roll; this means that weapon value de facto improves your chance to hit, but usually doesn't guarantee a minimum damage.
Humanity for Vampires vs. Morality for Everyone#
In Storyteller, Humanity is largely a VtM thing, not something applied across the system.
In Storytelling, all mortals start out with a morality mechanic, but it can be adjusted for different splats (e.g. the specific sins may be different between mortals and splats; names may also change).
Flaws
In Storyteller, Flaws give you Freebies immediately, and 'stay on', complicating the character's life when relevant (e.g. bad sight making vision-related perception rolls and some other rolls harder).
In Storytelling, Flaws don't normally grant any points immediately, but when a flaw complicates a character's life, that character's player receives an experience reward (with a limit on frequency).
Representation of Speed in Combat
Not something specific to any one splat, but while in Storyteller, characters who are significantly faster than others in fluff are also significantly faster in crunch, i.e. someone who's twice as fast as a normal human (whether due to time-warping, vampiric speed or whatever) acts that many times more often. In Storytelling, such representation is avoided.
A Word on Compatibility and Portability
The two systems are significantly more different than than the differences between any two of the pre-anniversary editions of World of Darkness Storyteller system variants. I would say that Storyteller and Storytelling are approximately as different as (pre-anniversary) Storyteller and Exalted 2e. A character made for one would not be playable in another without a lengthy conversion.
That being said, individual subsystems are at times close enough to enable portability - using a subsystem from one with minimal adjustments to use with the other. For example, it's possible to replace Nature and Demeanour with Virtues and Vices, or vice versa, and retain a playable system, and even be able to use many (most? all?) abilities intended for one with the other. Similarly, I've heard of people who use Mage the Awakening magick game mechanics to run a Mage the Ascension campaign, and say that the net effect from the change was an improvement. The portability of individual subsystem varies however - e.g. combat is so radically different that porting over mechanics from one system to another is likely to either break a lot of stuff, or require a lot of adjustments.