How comparable is a theremin to a synthesizer?

Yes, this is indeed not a “new topic”. But the deeper I study the technology and musical possibilities of the two electronic instruments in all their diversity, the more I am interested in the qualitative distinction beyond the obviously trivial like touchless playing. 

The theremin has no VCO, but a HCBO (hand controlled beat oscillator) with a certain "wavetable", different from common synth wave forms. It has no function like gate to ADSR, but an HMCA (hand move controlled amplifier/attenuator), which intuitively and naturally serves as an envelope generator and can also perform velocity/acceleration functions. The theremin is monophonic, that is a good idea, if you only can use both hands for pitch and volume. 

What do you think?

A theremin would be an extremely fun synthesizer I think, because all the waveforms you’d get would be organic and fluid provided you didn’t use pitch quantization of some sort.

Of course, you could probably get a somewhat similar result by using slider bars or by treating it like an ondes martenot, which would be easier to use for sure.

Theremin is not supposed to be easy though, and I hate to say it but it’s usually somewhat impractical for most applications. However, the qualities it can offer like complete fluidity are unmatched by other instruments.

Am I qualified to talk about the technical theory of electrical instruments? Not at all. But these are my surface level thoughts.

"A theremin would be an extremely fun synthesizer I think"  -- Trymeinchesss

It is!  Using capacitive fields to control a DSP synth is a blast!