class vs age class

class and age class both are nouns.

Word	Noun	Adjective	Verb	Adverb
class	Yes	No	Yes	No
age class	Yes	No	No	No

As nouns, age class is a hyponym of class; that is, age class is a word with a more specific, narrower meaning than class:

class (noun)	age class (noun)
education imparted in a series of lessons or meetings	people in the same age range
elegance in dress or behavior
a collection of things sharing a common attribute
people having the same social, economic, or educational status
(biology) a taxonomic group containing one or more orders
a body of students who are taught together
a body of students who graduate together
a league ranked by quality

class (verb)	age class (verb)
arrange or order by classes or categories