Is treason the criminal act against your country and "treachery" more personal, betraying a friend?

"treachery" is the more general term, that would apply to anything from personal betrayal to particularly underhanded business dealings. It's roughly equivalent to "betrayal", though more emphatic.

"treason" can technically refer to the same thing (you could say "this is treason" to refer to some personal act of betrayal, though it would come across as hyperbole), but in practice it almost exclusively refers to the crime.