Properly speaking, you may say that a novel is 'comic' or 'tragic', among other possibilities, and describe it as 'a comic/tragic novel', depending on its content, but to call a novel either 'a comedy' or 'a tragedy' is improper (a category mistake), because the terms 'comedy' and 'tragedy' name dramatic genres subject to rigid formal conventions that a novel, by definition, cannot satisfy. Strictly speaking, 'a comedy' or 'a tragedy' must be literary works written in dialogic form to be exhaustively represented on stage. The terms 'comedy' or 'tragedy' are nevertheless sometimes used to describe comic or tragic CONTENT, respectively, but only as mass terms, without the article 'a'. As to the difference between the comic and the tragic, roughly speaking, the comic makes spectators laugh (and learn from the folly of their likes) whereas the tragic makes them feel horror at the fate of their betters and experience compassion, with a catarctic and purifying effect on them. You should read Aristotle's Poetics. It is just about thirty pages; read it through if you can. If you cannot, parts 3, 5, 6, 13, 14 and 18 deal specifically with your question as originally formulated more than two thousand years ago.

novels are long stories but tragedies are long and most of lives is ending of tragedies.comedies are funny.

Brajesh, is this question some kind of joke? You know what a tragedy is. You know what a comedy is. Although I admit it can be difficult at times to distinguish between comedy and tragedy. When young, events in life look tragic, but when you get older you see just how ridiculous and funny it all was. This is a matter of changed perception. So you see, you can declare the novel as one or the other, there will always be people who have a different take on it.

They are the opposite of each other. A comedy makes you laugh while a tragedy makes you cry.

Dear brajesh ,Some of lives aren`t less than tragedy.Tragedy usually involves death and you can see the mean of it specially in our countries and in the Middle East.Some times peace in the lives does n`t seem possible.Some times nobody explain what went wrong or what is wrong .In the future some of our lives will been written as a novels or ... .Maybe our children in the future will be able to understand the reality and truth of tragedy or comedy of their lives.