1. There are no similarities between poker and slots. Except one: it's both gambling games.
All other things are different: one it's pure luck based game and the second one is skill based (with some influence of luck, but not on the long distance). One is solo game and the other is require more than one player to play.
1. You have to learn and improve your skills all the time and take advantage of your opponent's weaknesses in poker but when you want to fight the slot machines then you just have to press the lever and wait for your luck.
Again, you are the other users who can differentiate between poker and videopoker. You cant take any advantage of your opponent's weaknesses in video poker as your opponent is the house. What you can do in video poker is to increase your winning chance by choosing the best cards to hold. Video poker is a solo game, it does not require more than 1 player to play as it is a game where you play against the house.
But I suppose that even if you play perfectly video poker still has a negative EV right? If you play traditional poker then your EV can be negative as well, as it is the case for the majority of the players, but if you have enough skill and you find the right table then your EV can turn positive, also one of the great things about poker is the camaraderie and the conversations that you can have at the table, something that video poker obviously cannot emulate.