많아 [마:나] is a conjugation of a descriptive verb 많다 meaning "to be a lot, many" 만나 [만나] is a conjugation of an active verb 만나다 meaning "to meet" 1) The difference is the consonant meetup in the word 만나. As you see two ㄴs meet while on the other hand 많아 doesn't have that kind of a thing. 2) As I mentioned above by pronunciation, the difference is also the prolonged vowel sound. 많아 is pronounced as 마아나 and 만나 is pronounced just how you see it. Hope this helps :D

I would say that 많아 is pronounced like 마나.

in terms of pronunciation 많아 is pronunced as 만하 만나 is same as 만나 In terms of meaning, 많아 means a lot/many 만나 means meet up