OT: Pronunciation question for Brazilian Portuguese speakers

Oi!

Sorry for the non-conlang-related post, but this list is the only place
I know right now where I can find native Portuguese speakers to ask this
question of!

What I would like to know is: what is the difference in pronunciation
between the words "vem" (he/she comes), "vêm" (they come) and "vêem"
(they see)? Also "tem" (he/she has) and "têm" (they have)?

Muito obrigado!

Thomas