pronoun:an additional one of the same kind
I finished my cookie and asked for another.
pronoun:a different one; an alternative
If that plan fails, we will have to try another.
determiner:used to refer to an additional person or thing of the same type as one already mentioned or known
Would you like another cup of tea?
determiner:used to refer to a different person or thing from the one already mentioned or known
That's not my book; it must be another student's.
