Just because you're old enough doesn't mean you are man enough. You can be a 35 year old male but you can be acting like a kid so you are not still considered as a man. Age is not the only barometer of being a man, it is the way you act and carry yourself and also carry the people that is in your responsibility.
A real man is not partying 3 times a week, he knows his responsibilities especially if he has a family. He makes sure that before he have a good time the people that is relying on him will not suffer. It is ok with him if he cannot be with his friends at the weekend for as long as his family have something to eat everyday. On the other hand a boy doesn't care if his family gets hungry, what matters to him is he is happy with this life and he looks cool everyday. He will even prioritize his hobby before his family. He is a happy go lucky person and doesn't care if his life becomes miserable in the end.
A real man doesn't hurt his woman, he makes sure her woman is getting what she wants and always happy to be with his side. He makes sure her woman will be satisfied with his love and will never look for another man. He never hit her woman when they argue instead he is widening his understanding to fix their argument. On the other hand a boy is inconsiderate with the feelings of her woman. He doesn't mind if she cries and he is even proud of hurting her woman. He feels like he is really the boss in their relationship.
A real man knows how to take care of himself, he knows that if he becomes weak a lot of people will be affected so he make sure his body is in proper condition while the boy doesn't mind his health, he just eat what he wants and drink what makes him feel good. He doesn't mind the consequences of his actions. All he knew is he have to be happy and always satisfied. There is no filtration of the foods and drinks that he enter into his body.
A real man has goals and ambitions, he always dream of a better life and not only he dream about it but he also pursue it. He wants a better life for his family. On the other hand a boy has no direction, his motto is "come what may" he just go with the flow and accept what life has to offer him. He never grow and he doesn't mind if his life is stuck in a mud.
A real man is acting like a real man, he stay away from fights and nonsense altercations. He can control his emotions and he is mindful of his temper. He hates troubles and he is very patient in everything. Meanwhile, a boy is aggressive, he always find himself in trouble and he always think that he has the right to defend himself in every heated discussion. He never backdown to any fight to impress his girl and the people around him. He doesn't mind if he got hurt for as long as he fights back and look brave.
A real man always takes charge, if there is a situation where his decision and help is needed he never shy away from it. He is confident that he can pass any challenge that is on his way. On the other hand, a boy is always afraid of responsibilities. He will point another person to do the job. He is acting like he is brave but when difficulty arises he will look like a chicken.
The conclusion is if you are doing the right thing then you can be considered as a man. Being a man has nothing to do with age. There are even some younger guys at the age of 18 below who were acting like a man already. There are also people who were aging 40 above but still doesn't know how to behave like a real man.