The original FTB was an objective-based skyblock map, with progression heavily centred around EE2. These versions can be found in the retro SSP/SMP packs. The current pack is, eventually, intended to be for similar map styles, however the central EE2 mechanic is no more. Slowpoke has said that there will be more maps coming, when EE3 proper is released.
There is the new tournament map available too (I think you need to activate it through the maps section of the launcher), this is intended as a quicker, more intensive version, for tournaments, etc.