rein vs draw rein

rein is a noun but draw rein is not a noun.

Word	Noun	Adjective	Verb	Adverb
rein	Yes	No	Yes	No
draw rein	No	No	Yes	No

As verbs, rein and draw rein are synonyms defined as:

Other synonyms of rein include harness, rein in.

rein (noun)	draw rein (noun)
one of a pair of long straps (usually connected to the bit or the headpiece) used to control a horse
any means of control

rein (verb)	draw rein (verb)
keep in check	control and direct with or as if by reins
stop or slow up one's horse or oneself by or as if by pulling the reins
stop or check by or as if by a pull at the reins
control and direct with or as if by reins