Hi Priyesh,
Bachelor of Computer (BCA) is an undergraduate course which gives you insight into the world of computers and its applications. The duration of this UG program of 3 years of divided into 6 semesters which focuses on practiacl skills addressing problems arising in computer system and Mathematics also.
Bachelor of Computer Application assist student in gaining adequate programming knowledge and practices along with required theoritical knowledge.
So in short you will be studying more about practical in  BCA as compared to theory.
Hope it helps :)