They look pretty similar, two channel with separate tone controls, each having two modes:
As mentioned above:
- tremolo feature "speed" and "intensity" controls, RectoVerb doesn't have "tremolo".
- rectifier switch: you could choose "tube rectifier" or "silicon diode". RectoVerb is silicon diode only.
- channel cloning : If you like two modes on one channel, you could clone that one mode to the other channel. Kind of complicated. The Trem-o-Verb was the predecessor of what is now the "Road King" and "Roadster" which did away of "cloning" feature and uses 4 channels with independent tone controls.
- Trem-o-Verb has "Spngey" / "Bold" feature, lowers internal voltage. Not sure if the RectoVerb has this feature.
- Other than that 100 watts -vs- 50 watts.