Big differences:
WFRP characters are dirt poor most of the time.
D&D is about having HP gradually worn down hit after hit, while WFRP is about avoiding being hit or hopefully soaking all the damage of a blow. You activly defend by parrying atacks and possibly dodging. You have a chance of being whittled down, but taking hit after hit also means a good chance of triggering one of the games open ended damage rolls.
Armor in WFRP absorbs damage making armor really desirable. It lets you soak wounds: 1 {leather], 3{Chain over Leather] or 5 {Plate over chain over leather]
Characters do not skyrocket in power or durability.
*You start with 10-12 wounds, you'll end with 16-20.
*Damage does not increase very much at all. Start at 1d10+3 , end up at 1d10+6 or 7
*Before armor you soak two to three wounds per hit at start, later on you might be soaking 5, maybe 6 if you are lucky.
Player characers are special because they have fate and luck on their side{fate points],
not because their stats are much better than an NPC. The players use up fate points to survive otherwise fatal situations, wind up instead worse for wear, but
mostly intact. Those "fate points" also bestow "fortune points" which are used for rerolls and extra chances to parry /dodge.
Missile fire is dangerous.
Modern/Sci-fi "Run for cover you fool!" dangerous.
Magic is chancy to use and the civilized world loaths it. Any spell has at least a 10% chance of an unintended concequence. As a caster you can use it over and over, but you might not want to.
The WFRP encumbrance system needs work.