50 Ohm termination with active probe support, 500uV/div setting, I2S/etc decoding, a bunch of other obscure decoding formats, power analysis.
Adjustable bandwidth limits (the RTB can only do 20MHz, the RTM up to 20/100/200/350/500).
More acquisition modes (envelope/average + high res).
More trigger options (runt, rise/fall time, multi-channel trigger)
Storing failed mask testing segments.
Low/high pass in math.
Spectrogram option.
E:
significantly less blind time in segmented more, 200ns on the RTM vs 2.5us on the RTB