Hello Rama Krishna!
Both of the branches are highly different in terms of course and job profile.
In CSE you have to deal with computer software, computer programming or simply coding. You have to learn various coding languages and how to solve algorithms in various languages. Now depending upon your problem solving skills and knowledge of coding you have to create web pages, applications, robots, etc. This course is very interesting and it just requires your attention and an average to high end computer system with proper teaching.
In Mechanical engineering, your basics of Mechanics and mathematics must be sound and you must have the ability to excel in them. This course is mother of all as almost everything is teached in it but let me make you aware that learning everything isn't easy. You will learn Engineering Graphics, Tool designing, Thermodynamics and Heat Transfer, Higher Engineering Mechanics and much more technical stuff.
Now it's your interest which will make you decide that which branch is suitable to opt for.
Hope that helps!
Regular exam updates, QnA, Predictors, College Applications & E-books now on your Mobile