[RPG] What are some of the differences between 2e and 3e Mutants and Masterminds

The first summary comes from here:

Yep, there are 8 stats not 6 (fighting and agility are extra, and new); some things have been renamed — the powers get shuffled around into "effects", meaning that you create a "power" by picking what it can do, and adding it up. Thus Hal Jordan's power ring isn't a device with other powers, its a collection of effects that is the Power Ring power.

There are other things as well. For example, all characters can use things like Power Attack for +2/-2 for free now, but you need the advantage (read Feat) to use the full effect.

And then here:

Hokay, got the PDF. My thoughts:
• First off, this is from the recently released DC Adventures RPG, not M&M 3e itself. So we're probably just getting the "lite" version of the rules. Hopefully 3e itself allows for more customization.
• They give out less skill points, but that's because there's less skills; they shifted from narrow skill categories to really broad ones.
• They've renamed a lot of stuff... are they trying to divorce the line from the OGL? Because the d20 holdover terminology is, like, gone. Attributes are done like True20, even, not d20. (In other words, you just use the bonus for the stat... so Str 16 is now Str +3, for example.)
• Attributes are now Strength, Stamina, Agility (balance, grace, speed, whole-body coordination), Dexterity (hand-eye coordination, precision), Fighting, Intellect (formerly Intelligence), Awareness (formerly Wisdom), and Presence (formerly Charisma). (See what I mean about getting rid of d20 terminology?)
• Attributes go back to adding to adding to your attack and defense chance, and defenses have been split into Dodge (Ranged Defense) and Parry (Melee Defense). So, your Fighting bonus adds to melee attack and Parry defense, your Agility adds to ranged defense, and your Dexterity adds to ranged attack. So, its not like 'defenses and attacks are entirely separate from characteristics' like 2e. I'm not sure if I approve or disapprove.
• The combat maneuvers (All-Out Attack, Defensive Attack, etc.) may now be done untrained, by anyone, for up to a +2/-2 tradeoff. You still have to buy the feat (henceforth "Advantage", yes, they renamed feats too) to get +5/-5.

And an absolutely fantastic compilation here.

Some people talking about migrating back to 2e from 3e to provide a counterpoint.

And this is a good summary of all of the changes (I recommend reading the entire thread):

The biggest changes (actual changes not terminology changes) are the Attributes (8 now), Skills (only ~12 now), and power building. Powers are no longer even a little bit prebuilt, instead they take the Ultimate Power approach of giving you a bunch of effects and allow you to build the powers you want by combining effects, modifiers, and descriptors. This is nothing new but it see it in the core rules is a nice change.

The effects list has some big changes as well. Gone are the umpteen stun/dazzle/paralyze/confuse/et-cetera powers. Instead, there is a single "Affliction" effect with a myriad of well-balanced choices for the three possible levels of failure. Want to paralyze somebody with Atemi pressure points? Affliction (fortitude save) (hindered/ immobile/helpless)… which means 1/2 speed, 0 speed, defenseless and immobile. Want to blind somebody with a psychic attack? Affliction (Will save) (impaired/disabled/unaware)… which translates as -2 to checks with that sense, -5 to checks, completely unable to use that sense. Mind Control? Affliction (Will) (Dazed/Compelled/Controlled), etc., etc. It's the most drastic change to the game, but also hailed as one of the best.