A bigger difference is that Ukrainians want to defend Ukraine from Russia.
Maduro is a dictator. His first presidency was legitimate but he had to steal the last election and is now ruling by force, because he is so unpopular.
Majority of Venezuelan don't want to fight US. They want Maduro out and the person who actually won last election to rule.
US doesn't want to occupy Venezuela. They want a government that is aligned with US and not with Russia/China/Iran.
The goals of US and majority of Venezuelans align.