Specs arent going to make you a better photographer than your buddy.
Taking some phots might though.
My guess is they are all very similar cameras. The marketing is to make gearheads and noobs alike think they have a " choice" or make a " smart" decision.
More auto focus points, oh wee! High(?er) iso woop woop! A different, new ( ish) sensor, woooowie! Im in where do I sign up?
Let me suggest the 5D iii. Lots of second hand ones should be in the market soon as pros ditch them fir the iv.
Also to the OP Inbought my 70D months before the 80 came out and Incouldnt give less of a care about it ( 80) basically the same thing.
Common advice is to wait at least twongenerations or to move into a different category.
6d and 70,80,77 d are in the same category; Prosumer.