Psychologist

Bachelor of Arts vs. Bachelor of Science
So what is it that distinguishes a BA In Psychology from a BS in Psychology? A B.A. In Psychology Involves More Liberal Arts Courses
Generally speaking, a Bachelor of Arts degree focuses on more liberal arts general education courses. Students who choose this degree may also be required to complete a foreign language component. The BA Option usually involves taking fewer courses in psychology and more classes in subjects outside of the major field area. A BS in Psychology Requires More Science, Math, and Psychology Courses
A Bachelor of Science degree will focus on more Science and mathematics courses. Students pursuing a BS in Psychology may have to take more lab and statistics general education classes. The BS option involves a stronger concentration on the major area of study and students take more psychology courses than those who are pursuing a BA. The subject-matter area of the degree may also focus more on research methods and applied psychology courses.

Hi
Yes, you can go for M.A. (Psychology) after your BPT. Eligibility for M.A. (Psychology) in most of the top universities is pass with 50% aggregate marks in Bachelor's Degree. (It may vary with the University you choose)
The main aim of M.A. (Psychology) is to provide understanding and the answers to the complexity of human behavior with broad focus on psychological testing, Psychopathology, Health Psychology, Positive Psychology and Organizational Behavior etc. You must make sure that you are enrolling yourself in a premium university that provides you access to ample growth opportunities. Some of the top universities for M.A. (Psychology) are:
Jesus and Mary College, Delhi. Lovely Professional University, Punjab
St. Xavier's College, Mumbai. Presidency College, Chennai. Christ University, Bangalore. I hope it helps.