In my opinion, there are no similarities, each of these games has its own advantages in betting, sometimes this depends on each gambler, of course those who are more familiar with them will take precedence.
Regarding skill... I think poker is more dominant with additional skills and uses our brain to think more than slots.
But to myself... I prefer to slot games, because I'm more familiar with slots, and it's simpler, just pressing on without thinking more like in poker.