How can I determine if a passport from Ghana is real or not?

It's not real.

You can not, it will look so real (photo copy) that even government could not, if it is done by a real first class company.

The fraud companies are often large companies, with computer programmers, special girls used just for doing video calls.

They will have large group of computer users, that email 1000's of emails every shift. And answer 100's of personal emails. Also often you will or may chat with different people, who merely look up your prior chats, use preset answers and so on.

Next if they are sending and showing you a copy to prove they are real, then they aren't.

IF they are asking you for money, they are a scam. Also it is normally obvious from the amount they ask for. If they ask for much over 300 USD for visa and so on, it is a fake.

They also use real passport often, that they pay to use or steal or have gotten photo copies.

Next, why would a great beautiful girl decide she "loves" you from a few emails. Even if it was real, she just wants a ticket out of Ghana and a green card. So once they had a card they would be gone ( if they were real)

Bwaaahahahaha... how much money did you lose so far? You aren't EVER going to see "her" or your money ever again. This is almost as Famous as the Nigerian scam. This is a well known scam.

Google ghana romance scams. See for yourself.