Difference between TENS and EMS programs?

I'm tired of the junk that's out there in the low-priced E-stim market, so thinking about getting a commercial TENS unit. Then I discover that some models also have an EMS program in them for muscle stimulation. I'm very interested in that as a way to flex my calf muscles and prevent edema since I spend so much time in a wheelchair.

I'm wondering if a commercial combination TENS/EMS unit would also have the capability of providing me with some good E-stim thrills that the cheap boxes I've foolishly invested in so far haven't done.

All info appreciated. TIA.

ldb

I am about to try this. Arrives today from Amazon:

AUVON 4 Outputs H1 TENS Unit 24 Modes Muscle Stimulator for Pain Relief, Rechargeable TENS EMS Machine with Easy-to-Select Button Design, 2X Battery Life, Dust-Proof Bag and 8 Electrode Pads

I made my own stereo mp3 power box with plans from smartstim some yrs back.

My stereo box works well, but wanted something portable. Estim done safely can be fun and a gain for sexual health.