Obvious that Ladybug is marinette and that Cat Noir is Adrien. Like come on! Their hair style, their mouth, eyes and all that are same! Everybody should know who they really are!
Actually the Miraculouses have a special kind of magic that makes sure that nobody recognizes the holders, in hero from or in civilian form. This is officially confirmed in the wiki.
The reason Adrien cant tell Marinette is Ladybug is because in the time breaker episode * after LB went back in time with timebreaker* Adrien SAW ladybug when she was on higher ground when she yelled at Chloe to not play with Alex's watch and Adrien THINKS that LB is not Marinette becahse Marinette was holding the banner NEXT to him.
