Variants decided by five-card hands.
Every poker variant is decided by five-card hands. Hand ranking, from highest: straight flush, four of a kind, full house, flush, straight, three of a kind, two pair, one pair, high card.
When two players hold the same type of hand, the card ranks decide. A pair of kings beats a pair of tens, and if the pairs are equal you compare the side cards. With two pair you compare the highest pair first, then the lower pair, and finally the fifth card. Straights are compared on their highest card, flushes on the highest card and then the next highest. In traditional poker the suits never matter.
How a winning hand is rewarded differs — some variants bet chips, others score points. That is covered in each variant's own rules.