No, Question level of ISRO and BARC are not similar. For BARC written exam prepare some extra topic from C++ (basic concept of OOPS, constructor, destructor, polymorphism etc), Java (basic program from output finding, last year 2 question from output finding, one from the thread topic).
Actually, they can ask any subject from CS (including gate syllabus) which you have read in the 4-year in Your BE/BTECH program.
