Changes since the original CvSX...
The return of air blocking.
Ratio System traded in for a three player team like the KoF games.
Lots more characters.
An actual story.
Individual Endings (Why has Capcom stopped doing that?)
Much less "watering down" of the SnK fighters.
"Power Up Modes" like Vampire Savior's Dark Forces. Done by pressing HP and HK at the same time. They take up a Super Meter, and you can't do a Super Move or Power up you Super Meter while it's in effect. You can turn it off early by doing the Power Up motion again, though.
Powering up the meter in SnK Groove is now done by pressing D+HP+HK. Trust me, this works.
Dashes are slightly different, they start with a quick hop, like befor, but then you keep running. This way, you could have just a quick burst, or a long run.
Taunts in SnK Groove now depleate from your opponent's Super Meter. This is really good for Dan, since his taunts add to HIS Super Meter.

Ideas that remain from CvS.
The Groove System:
Capcom Groove
3 levels of Super Meter that is charged up by attacking and being attacked.
Three levels of Super Moves that are determined by your current Super Meter level and wether you press the Light Attack buton, the Hard Attack button, or both buttons for activation.
SnK Groove
A one level meter that is charged up by getting hit or by "Powering Up" by holding the HP and HK buttons. You are completely vulnerable while charging up.
When you life meter reaches a certain point, you have unlimited level 1 Supers. If you are at this "Despiration Point" with a full Super Meter, you get a Level 3 Move!

Other points
Rolling and Dashing are still in.
So is Taunting.
Each rounds starts with the characters doing a special "Intro Pose" or "Opening Taunt," but when certain characters get together, the intro is different.