what is the difference between real or fake bitcoin company? how can we conclude that A company is fake and B company is the real one 
A bit confused what you mean there, how can you have a fake bitcoin company and a real one. Are you asking how to determine if someone is giving you real bitcoin or not?
Well, the answer to that is pretty simple. Right now there isn't a lot of people who have enough knowlodgege of bitcoin to fully recreate it so that means no one can ever scam you with a fake version of bitcoin.