Tomato TOR-VPN vs BT-VPN difference to access tor (onion) network

Hi, I was wondering what the the Tor-VPN tomato does when my current firmware can open Tor Browser just the same?
Tomato Firmware 1.28.0000 MIPSR2-115 K26 USB BT-VPN

I've looked at this http://tomato.groov.pl/download/K26RT-N/build5x-099-EN/builds.png
But I still have no idea what the diference (if any) is. Is there a worded guide to the different features on different tomato builds? thanks