Guilt and blame are sometimes interchangeable. When they refer to the responsibility for an action, for example, the meanings are the same.
I am to blame for the accident. = The guilt for the accident is mine.
To blame = to accuse or assume that someone has done something illegal, immoral, etc.
To be guilty = to be responsible for having done something illegal, immoral, etc.
I have been blamed for (accused of) the theft, but I am not guilty (I am innocent) of the crime.
I am guilty of (responsible for) the crime, but I have not yet been blamed (accused).