A chess engine generates moves, but is accessed via a command-line interface with no graphics.
A graphical user interface (GUI) allows one to import and load an engine, and play against it.
A chess database allows one to import, edit, and analyze a large archive of past games.
This list contains only chess engines for which Wikipedia articles exist yet and therefore is very incomplete.
It does not reflect or imply current or historic play strength as this characteristic in itself usually does not warrant an entry on Wikipedia.