The Revolve is the Replicape evolved. At least that's how Elias describes it.
Revolve is to Replicape what Rambo was to RAMPS. Instead of having 2 boards, you end up with only 1.
This gives the opportunity to wire things differently and in a more interesting manner than what was possible using only the GPIO of the Beaglebone Black.
For example, gone is the micro-HDMI port. Now it's a full-sized connector. Instead of 1 USB, there's now a hub with 4 ports available. There are UART and I2C connections available with Grove connectors. There are 2 external stepper headers, as well as for a quad-encoder.
The full design is on Github