To answer the original question, Q4F is a faithful re-creation of TF (a Quake 1 mod), whereas Q2WF was more a spiritual successor/evolution of Q1TF (WF was made as a fill-in for those who wanted TF gameplay in Q2 when it was announced that TF2 would be a standalone game..)
WFA evolved further from Q2WF, and WFR promises to continue that trend of adapting and improving on the last iteration.
Q4F is basically just Q1TF with new maps & models in a new engine. They cater to the hardcore Q1TF crowd that found WF to be too gimmicky or spammy, or just too different from their beloved TF.
Two different idealogies, there's no way they could ever merge without one group abandoning their ideals... And even then, somebody else would most likely step in and fill the void.
=V3=