Variants or Counterparts are characters that are separate, but generally share the same identity with another character to some extent.
An example of such is Batman. There are many incarnations of Batman.
Above are three different characters: from left to right, Batman (Nolanverse), Batman (Arkhamverse), and Batman (Timmiverse), but all are the same. Each Batman are Bruce Wayne all from their own individual universes and story-lines.This makes them General Counterparts.
All Characters Wiki also includes a different set of counterparts that relate characters further. Counterparts can also be related if they share the same actor. To provide an example, Adam West did the voices for Batman (1966 TV Series), Catman (The Fairly Odd-Parents), and Mayor Adam West (Family Guy), thus making them Vocal Counterparts.
Finally, Perfect Counterparts are when the two counterparts are both General and Vocal Counterparts, such as Batman (Arkhamverse) and Batman (Timmiverse) both are Batman and play as Kevin Conroy.