internal-lisp-face-equal-p

internal-lisp-face-equal-p is a built-in function in `C source code'.

(internal-lisp-face-equal-p FACE1 FACE2 &optional FRAME)

True if FACE1 and FACE2 are equal.
If the optional argument FRAME is given, report on FACE1 and FACE2 in that frame.
If FRAME is t, report on the defaults for FACE1 and FACE2 (for new frames).
If FRAME is omitted or nil, use the selected frame.