One of the possible effects of the wand of wonder magic item is (emphasis mine):
You enlarge the target as if you had cast enlarge/reduce. If the target can’t be affected by the spell, or if you didn’t target a creature, you become the target.
There are multiple possible effects for the wand of wonder that use a similar wording. There are also many possible effects for the wand that say instead that "you cast [spell]".
Mechanically, what are the differences between the two wordings (if any)? What exact aspects of the spellcasting process/effects are different between the two?