As far as I remember, but could be wrong. I didn't use EFKE developers for some time now...:
FR16 is liquid universal developer (for film and paper), I have now about one third of bottle of concetrate. Working solution mix is 1:4 for paper and 1:9 for film (or vice versa, don't know till see at manual), and develop 10 roll films or 1,5 m2 of FB paper. I used it only for develping paper and only contact sheets. Cheap (liter of concentrate is about 6 EURO in my town), fast to mix, and can stay good in working solution long. But as I say I used it only for contact sheets.
FR3 is "fine grain" powder developer. I used it with Ilford delta 100 and I was happy with it. It can stay good over 6 months as working solution. I didn't diluted it ever, only used it in working solution mix. Devop 10 roll films in 1 liter of working solution. Some people here say it is D76/ID11 developer, but I don't have any "official" confirmation about that.
I hope I didn't mix informations in my head...
Others I don't know...