Whoa, easy, it's nothing that extreme.
Aside from a ton of new fluff text in combat, depending on various variables like damage dealt, position or bodypart hit (helloooo, groin kicks!), it got a bunch of tactical elements mixed in.
Essentially, your intent matters now. If you're on Help, you're caught off-guard, so any hits against you can't be dodged nor blocked, and you get the full impact of the attack.
The remaining intents form a rock-paper-scissors triangle (Disarm>Grab>Harm>Disarm). Disarm means you cannot block but can dodge and you can break grabs and, I believe, makes the push chance slightly bigger against a grabber. It also increases the delay to upgrade the grab on you for the grabber relative to Harm and Help.
Grabs make you take less damage from Harm attacks by the grabbed person and takes less time to go to an aggressive grab like for Help. The person you grabbed loses the ability to dodge, so your hit chance is much better. It has the same grab upgrade time as for Disarm. You can block in addition to dodging.
Harm is pretty straightforward. You can block. Disarm and Help are at a disadvantage, since they cannot block. If you get grabbed, your damage and defense both go down.
Furthermore, bodyparts you target matter more - head hits do more damage and make your vision blurry, arms/hands make you drop whatever's in them, chest do LESS damage, but give you the chance of your opponent reeling from the impact (it's the Weaken effect), groin shots cause a lot of pain and leg shots cause pain, albeit three times less than groin shots, but three times their damage.
Those bodypart buffs are all based on the blessing on the blessing of RNGesus, though, so it's not a per-hit thing.
E: Oh yes, and aggressive grabs got, at least allegedly, fixed, in that you can't just walk out of them anymore, you have to resist/disarm your way out.