The only difference seems to be the Turbo B-Clock, which supposedly allows the user to change BCLK frequency. Also it appears the K7 lists support for DDR4 3600 with OC, although the memory support list suggests that any 3600 memory would be downgraded to 3200.
As far as I know changing BCLK is not really recommended with Ryzen and you won't really need it anyway since you are still able to overclock with multiplier.
So, assuming you won't use 3600 memory there is really nothing to justify a K7. Chances are Gaming 5 will also get 3600 Mhz memory support in the future, but don't take my word for it.