Not sure why this swap was committed https://www.inaturalist.org/taxon_changes/13814 (citing Calflora) because Calflora (along with every other reference I can find now has these as separate species).

Unfortunately, looks like they are largely sympatric so location isn't going to help much sorting these observations.

FNA provides the following:

Ephedra aspera: Twigs usually scabrous; bracts of pollen cones yellow to red-brown; seeds smooth to slightly scabrous.
Ephedra fasciculata: Twigs smooth or very slightly scabrous; bracts of pollen cones light yellow; seeds furrowed.