IMHO, the biggest tactical differences from WWII to today are all related to the greatly increased lethality of weapons (ATGMs, TI sights, etc.). "If you could see it you could shoot at it" has become "If you can see it you can kill it".
Operationally, the big differences are 24hr ops instead of a slowdown at night and the increased depth of operations. That really had it's start in WWII with the para- and glidertroops, but has become more feasible since the advent of helos. The best recent example would be the insert the 101st AAslt did in Iraq. Nothing freaks commanders worse than enemy troops in the rear (areas)!