[Python] Difference between `return iterator` and `yield from iterator`

I'm trying to implement my own version of itertools.compress, the problem is that i stumbled upon the return type. I mean both of these functions return an iterator, but i think the second one is not considered a generator function because there is no yield statement inside. So my question is, are these two implementations equivalent ?

def compress (seq, selectors):
from operator import itemgetter
fst = itemgetter (0)
snd = itemgetter (1)
yield from map (fst, filter (snd, zip (seq, selectors)))

def compress (seq, selectors):
from operator import itemgetter
fst = itemgetter (0)
snd = itemgetter (1)
return map (fst, filter (snd, zip (seq, selectors)))

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