These two words are sometimes interchanged by students, but they are two different words that have different meanings.
1a. LATER (adverb)
Comparative of late meaning after a particular period of time, the present time or the time being discussed
Examples: Let’s talk about that later.
He promised to call later.
1b. (Interjection)
It is used to say goodbye.
Example: See you later.
LATTER (adjective & noun)
Being the second of two things mentioned.
Example: Regarding captain and major, the latter rank is higher (i.e major is the higher rank of the two mentioned)
