You're not the only W:ET veteran here
I think they mentioned that the standard 'walking speed' a little slower is than in W:ET, but the SMART system will make up for that.
Medics also give full health/health buffs in stead of 20hp. People can revive themselfes after receiving a syringe. Soldiers have a shielding ability and hand out ammo (No field ops) Soldiers are also able to blow certain things up. Engineers can deploy turrets and buff weapon damage. Operatives get a hacking tool. There's a lot more to say about class changes, don't know them all by hard.
Another major difference with W:ET is the introduction of body types. Lights move faster, have less health and can use 'less heavy weapons'. Light are limited to SMG's as primary and a pistol as secondary. Heavies will be able to use all weapons with a better secondary (F.e. mini gun + assault rifle). So in this game, you can be a medic with a grenade launcher (which is not OP)
The focus is more on teamplay: They designed the XP system to be more rewarding for people actually helping teammates.
Just to add to his post, "Short rifles" are also a light weapon. These are semi-auto or bolt action rifles with good accuracy. Similar to the Garand or K43 in W:ET. With weapon upgrades, you can give them a scope, to make them akin to a sniper, but headshots won't kill in one shot.
Each bodytype is able to carry one main weapon of up to their weight-class, and one weapon of a lower weight-class. Lights are limited to a light weapon and a sidearm, mediums can use up to a medium main and light secondary, and heavys are able to carry any weapon as their main, with a medium or lighter secondary.
Off the top of my head:
Sidearm - semi-auto pistols, machine pistols, revolvers
Light - SMGs, Short Rifles
Medium - Assualt rifles, pump action shotguns, single-shot grenade launchers
Heavy - Machine guns, Auto-shotties, "Automated Grenade Launchers", Even a minigun, maybe more