These are the common cords you'll find.
S cord = Service cord
SJ = + Junior (thinner jacketing)
SJO= + oil resistant jacket
SJOO = + oil resistant inner and outer jacket
SJOOW = + water resistant
SJOOWT = + thermoset plastic
--Or any combinations of this alphabet soup.
To add to the confusion--
A 12-3 S-cord (a cord) has 2 conductors + an equipment grounding conductor. (white, black, green)
A 12-3 Romex (a cable) has 3 conductors + an equipment grounding conductor.(white, black, red, bare or green)