Honestly, which board you do doesn't really matter cos Universities just want the
grade.
CIE Math is tough and more in depth. Edexcel Math is
comparatively easier but easy (remember that).
-CIE Math has 2 papers: P1 which is compulsory and M1/S1 (depending which you choose).
-Edexcel Math has 3 papers: C1,C2 and M1/S1 (depending which you choose).
Good luck! (:
I hope I was clear enough!