The variants usually differ in the minimum necessary hand needed to win, and possible special wild cards. For example, Jacks or Better pays for a minimum hand of two jacks. Deuces Wild has the 2 as a wildcard, and the payout usually starts at a higher-valued hand, such as two pair or three of a kind.
The types can also differ in their payout rates, as the house edge will be different. Some games have a higher house edge and higher risk, but in turn may pay out a higher potential jackpot, or even a progressive jackpot.