I can't tell the difference between the red and yellow cleats, and the yellow cleats seem to work fine
I have the (previous) pro-peleton version and assume them to use more or less the same mechanism-- despite different manufacturing and the resulting aesthetics. The pro cleats were the basic yellow with just the addition of the thin steel carbon sole protector. When the new pave version came out I asked Speedplay if there was a difference between the red and yellow and their response was
"Thank you for contacting Speedplay.
There is a difference in cleats.
You can use a Pave cleat with Zero Pedals, but not Zero cleats with Pave pedals.
Any further questions please feel free to contact us again."
Since I don't have any red-cleats I can't comment on the differences but might suspect that the red might have a slightly different C-ring.