Difference between Do someone honor and Do the honors

do someone honor—

1. pay deserved tribute to a person:

• Twenty heads of state attended the Queen’s coronation to do her honor.

2. (of smb.’s action or behavior) add to a person’s reputation (also: do someone credit):

• Her behavior in such a difficult situation does her honor.

do the honors—act as the host; serve one’s guests:

• You do the honors and pour out the tea while I bring in the cakes.