Both drama Male leads are chef in profession .
Both male leads train female lead for better cooking skils.
Both dramas have cute romantic scenes.
Both dramas have happy ending

First of all.Both dramas are CLASSIC MASTER PIECE in my opinion.
Both drama main leads are dealing with infidelity issues. But totally in different ways.

In secret love affair Female lead is much older than male lead.
My Mister male lead is much older than female lead.

In secret love affair Female lead is dealing with office politics.
My Mister male lead is is dealing with office politics.

Both dramas have many heartwarming and heart breaking moments.

Main similarity, YOO AH IN from secret love affair and LEE SUN GYUN from my mister has insane acting skills.Both are not talking much in both dramas but their expresions talking 1000 words.