Well, this is the case because one is comparing apples and oranges.
A fixer is a specific type of job (think Olivia Pope in the tv show Scandal) who is responsible for subtly negotiating problems.
A lawyer is a member of the bar of a State who represents a person on a legal matters.
So, while Michael Cohen is/was a barred member of the law community he was not acting as a lawyer for President Trump.
