Yes, there are some differences, as I can tell from my humble experience.
Obviously having three VCOs of the Voyager makes quite a difference and generating a “richer” and “smoother” sound is easy by just using all of them. The sub-oscillator of the Sub37 does a good job, but it can’t substitute a full-fledged third VCO.
The VCOs of the Voyager are more unstable. It’s not much after warming up, but I guess, that little more “floating” makes a difference for the overall sound too.
The LP filters are ladder-filters and similar. You can switch between 1,2,3,4 poles. But there could be differences, which I never checked.
Nevertheless, the Voyager reacts differently, if the headphone output is used to overdrive the filter. There are some formant like sounds to be discovered, that I have missed on the Sub37. It’s a weak effect, but there is something subtle. The two options for “overdriving” on the Sub37 make the sound much more grittier and dirtier, self-oscillation is feasible, but it’s definitely not the same effect compated to the Voyager - soundwise.
TBO I have not made a one by one comparison until now and maybe for scientific reason I should do it. I use the Voyager for all those lovely classic moog sounds - and also - for many sounds going beyond a Model-D.
I agree, the sounds of the Voyager are smoother by nature, if compared to the Sub37. There is sonic territory, where both can sound similar, but if more agressive, gritty sounds are required, the Sub37 is my candidate of choice. I am happy to have the oportunity to use both of them … 