course vs course of action

course and course of action both are nouns.

Word	Noun	Adjective	Verb	Adverb
course	Yes	No	Yes	Yes
course of action	Yes	No	No	No

As nouns, course and course of action are synonyms defined as:

course (noun)	course of action (noun)
a mode of action	a mode of action
education imparted in a series of lessons or meetings
facility consisting of a circumscribed area of land or water laid out for a sport
(construction) a layer of masonry
part of a meal served at one time
a connected series of events or actions or developments
a body of students who are taught together
general line of orientation
a line or route along which something travels or moves

course (adverb)	course of action (adverb)
as might be expected