Father surrogate and Stepfather

Father surrogate noun - A man who takes over all the functions of the real father.

Stepfather and father surrogate are semantically related. In some cases you can replace term "Stepfather" with "Father surrogate", this terms are similar.

Stepfather noun - The husband of your mother by a subsequent marriage.

Father surrogate and stepfather are semantically related. Sometimes you can use "Father surrogate" instead a noun "Stepfather".