Breadth of Option
Unexpected monster rears out of the darkness, clearly well beyond the battered party's ability to handle?
Wizard teleports home. Fighter manages to kill the thing half to death before he gets eaten.
Ambuscade! The earl's men have the party cornered, and demand they surrender - only execution awaits if they do.
Wizard casts glitterdust - blinding most of the enemies and allowing his comrades to cut them to pieces. Or he turns invisible and leaves them to their fate. Maybe he uses a colour spray, and stuns half of the enemies, or burning hands to kill a different half. Maybe he runs away, and leaps off a cliff while casting featherfall. Fighter faces down 15 halberds and hopes to god his HP and AC hold out long enough for his Cleave feat to cut through them, because other than hoofing it, that's his only option.
It's less true, but still prevalent, at low levels, that Wizards can escape or defeat situations that kill fighters. At levels past 7, though, once Wizards get vastly more powerful options, foes become deadlier in melee than the Fighter, and Wizards can prepare enough spells to prepare for many different circumstances, the gap widens enough that the two classes are, barring self-nerfing/DM hand on the scales, playing different games.
The arguments against this generally incorporate self-nerfing. I've personally had first-time players pick the better spells on the wizard spell list, reliably. Animate Rope is indeed a wizard spell - but new players can easily see that it's utility compared to Burning Hands is very low. Fire Trap, Detect Scrying, Dimensional Anchor, Arcane Eye - all have uses, but new players pick Polymorph, and some of them even turn into hydras. Literally first-time players. There is a wide-spread culture of casters intentionally playing weaker than their class options offers them, especially amongst 'traditionalist' DnD players. This is to avoid GM banhammer/fudging the rules to smash them, generally, and has dated back to the earliest days of DnD.
Wizard spells are stronger than fighter options for less action economy (standard vs Full-Round), they can use them from range instead of their best tricks requiring melee, they can target groups, single targets, saving throws, hp, AC, no save at all,line of sight/effect blocking, creating minions, destroying enemy weapons/shields, altering the battlefield, and decide which to do on the fly instead of needing feat chains (that are still inferior to spells even if you have them), they can layer buffs to be tougher in every way than a fighter, they can use spells to be faster in every mode of movement than a fighter, they can literally see things before they happen and set up the perfect counter, spy on people from far away, turn enemies into allies, read minds, solve every single kind of encounter, create armies of minions (even without cheese, the literal lesser planar binding spell, the literal Dominate Person spell), turn into a gas and slip through the keyhole of doors, you know, whatever they like.
The sole 'downside' for this real ultimate power is that they can only use so much of it before needing a naptime. And since they can teleport home, or use spells to secure a safe place to nap, and since killing defenseless parties is kind of a dick DM move, in effect this is not a big deal without time pressures. And even if you can consistently use time pressures without it negatively impacting the story, you still have to effectively read the wizard's mind - as without his spells being used, an 'easy' encounter can swiftly lead to a TPK (at least, of the non-teleport/invisibility/gaseous form capable members of the party). Which is again bad DMing.
Individual wizards might self-nerf into being fighter-level, but the wizard class is a powerhouse of might. It becomes godlike, odin or zeus while the fighter stays firmly in hercules territory. But even at low levels, the wizard has options the fighter doesn't, and at everything but 'random damage comes out of nowhere! you take hp loss' has choices that will keep him alive instead of choices that lead to him relying on dice rolls against AC in order to not die.
I know of no official conversion, as of writing. However, were I to write a conversion, I would begin by comparing the stats from D&D 3.5, where the astral dragon appeared in Dragon magazine issue 344. I would then use that to adapt an existing 5e dragon (which for copyright reasons I won't replicate here).
The astral dragon is approximately as strong as a brass dragon of similar age, and we can use the 5e statistics for that as a basis, modified as follows:
- Breath Weapons (Recharge 5-6).
- Scouring Dust. A cone of scouring dust (as the standard dragon's breath weapon, except that the damage type is slashing).
- Psychic Wind. A 5 foot wide line of dark cloud. Affected creatures must make a saving throw or be affected by psychic wind, as per the Dungeon Master's Guide p. 48.
- Severing Bite. On a critical hit with its bite attack, the dragon instantly severs an astral traveler's silver cord, killing them instantly.
- Detect Extraplanar. The astral dragon has advantage on Perception checks made to detect creatures who are not native to the astral plane.
- Lair Actions. An astral dragon makes its lair on some chunk of matter floating in the astral plane, often the massive petrified body of a dead god. On initiative count 20, the dragon causes one of the following effects:
- All gravity within 60 feet of the dragon is nullified. All creatures' standard walk speeds are reduced to 10 feet, and creatures in the air who lack a fly speed simply float in place.
- Astral wind buffets all creatures within 20 feet of the dragon, pushing all creatures 20 feet in a direction chosen by the dragon.
- Regional Effects. The region containing a legendary astral dragon's lair is warped by the dragon's magic, which creates one or more of the following effects:
- Psychic Wind. Creatures approaching within six miles of the dragon's lair are affected by psychic wind (DMG p. 48).
- Tidy Nest. If a creature not native to the astral plane is slain within 1 mile of the dragon's lair, its body is banished back to its home plane. There is a 20% chance it will be sent to another plane. Any gold or magic items the creature was carrying are not banished.
Astral dragons are always of Neutral alignment. They consider themselves guardians of the Astral Plane, and consider all non-native visitors to that plane equally their enemies.
Best Answer
Wizards study, Sorcerers know
Wizards practice learned magic. They study for years to learn how to manipulate the weave and become masters of it.
Sorcerers practice innate magic. They are gifted with an ability to manipulate the weave, and sculpt their interactions with it.
Class features
Wizards use Intelligence as a spellcasting modifier, while sorcerers use Charisma. These abilities are associated with different skills, so that difference may or may not be important to a player.
Wizards know more spells, and prepare a subset of those spells to cast each day. A wizard learns 2 spells per level, and starts with 6 at level 1, totalling 44 spells known. They prepare a number (INT+Level) of spells from that list each day to be able to cast. Wizards can also copy spells from spellbooks and scrolls they encounter, adding those to their spells known.
Sorcerers know fewer spells, but can always cast them. Sorcerers learn a total of 15 spells, but they're always able to cast them if they have spell slots available.
Wizards can cast more spells per day through their Arcane Recovery class feature. They restore a number of spell slots when they take a short rest.
Sorcerers can sculpt their spells to behave differently. Sorcerers have access to Metamagic, which allows them to increase the damage, range, or duration of spells, grant disadvantage on saving throws against them, cast silently, or affect an additional target.
Sorcerers learn more cantrips than wizards.
Wizards can cast spells as rituals, taking 10 additional minutes to cast, but without using a spell slot.