course session vs class period

course session and class period both are nouns.

Word	Noun	Adjective	Verb	Adverb
course session	Yes	No	No	No
class period	Yes	No	No	No

As nouns, course session and class period are synonyms defined as:

course session and class period: a regularly scheduled session as part of a course of study

Other synonyms of course session include recitation.

course session (noun)	class period (noun)
a regularly scheduled session as part of a course of study	a regularly scheduled session as part of a course of study