What are the different classes of nouns?
Anything is a noun.
Just keep in mind that anything is called noun.
Above the sentence, please count it---total 9 words.
each and every word is a NOUN!
Are you surprised?
KEEP, IS by functions in a sentence here they are acted VERBS. clear?
Called is a participle, but see the dictionary a verb, keep---it is a noun.
So 8 parts of speech all are nouns, but by functioning they are not so.
To memorizing, Oh, how many types of nouns in our grammar book/s, it is WORTHLESS unless you understand the morphology of English grammar.
Of course, in our school I mean at early level we memorized them to understand to further understanding, clear?
If you are an early stage bird, my suggestion, go --no problem.
Follow Wren and Martin grammar book to know all---like --COMMON, PROPER, MATERIAL, CONCRETE, ABSTRACT etc etc. all for having an exam score.
But if you like to write English confidently, sorry, unless you know the FUNCTIONS OF EACH word in a sentence, which one is which parts of each a part of speech, then your memorizing of classification these and those are worthless.
And, it is the number one of reasons why many native speakers write English incorrect way ( of course, many write correct ways too!) where a non native it is simple as he has to put much hard labor than a native educated one to understand the morphology! I usually research them---why as it is one of my daily tasks too.
Now, learn by your requirement.