Futaba Combo

Hi,

I would like to purchase one of these options for my Hitec Optic 6
but I don't know how to get there, what is the difference between
the FrSky FF-1 2.4Ghz Combo Pack pour Futaba w / Module & RX, ref:Futaba-Combo, and the FrSky DF 2.4Ghz Combo Pack pour Futaba w / Module & RX  Ref:DFT.
Thank's in advance
Cordially
Jacques

https://hobbyking.com/fr_fr/frsky-ff-1-2-4ghz-combo-pack-for-futaba-w-module-rx.html

https://hobbyking.com/fr_fr/frsky-df-2-4ghz-combo-pack-for-futaba-w-module-rx.html