Hello @sharonwelter1, Welcome to Connect. In my non-expert opinion I think they are a little bit similar but a lot different in how well they work. Here's some basic info that explains it a little.

"TENS and SCS produce similar effects in neuropathic, inflammatory and non-inflammatory muscle pain models while MA is only effective in inflammatory and neuropathic pain models."
-- Transcutaneous electrical nerve stimulation, acupuncture, and spinal cord stimulation on neuropathic, inflammatory and, non-inflammatory pain in rat models:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7136295/
There are some discussions you might want to read through to ask questions of members who have tried or are using a spinal cord stimulator or TENS unit.
-- Comparison of Spinal Cord Stimulators from Boston Sci., Nevro:
https://connect.mayoclinic.org/discussion/comparison-of-spinal-cord-stimulators-from-boston-sci-nevro/
-- Spinal Cord Stimulation:
https://connect.mayoclinic.org/discussion/spinal-cord-stimulation-3/
-- TENS Units:
https://connect.mayoclinic.org/discussion/are-tens-units-any-help-for-chronic-pain-andor-pne/
Have you been looking at getting spinal cord stimulator or a TENS unit to help with chronic pain?