What is the difference between Grand Theft Auto Liberty City stories and Grand Theft Auto episodes from Liberty City?

Liberty City Stories was made for PS2 on top of the GTAIII engine, when GTA Episodes from Liberty City is an add on content made for XBOX360 version of the GTAIV having two episodes: "The Lost and Damned" and "Grand Theft Auto: The Ballad of Gay Tony"

Both add-on episodes for the XBOX360 were also released as a standalone game called Grand Theft Auto: Episodes From Liberty City that does not require the original Grand Theft Auto IV media to be playable.