Hi!
Yes, there is a difference between theoretical astrophysics and theoretical physics. Not only in the topics, but also in the techniques used in research. Theoretical physics applied to astrophysics can only be done in certain topics in theoretical physics, as some physics disciplines are not important at all for astrophysics. In general I would say doing the astro variation will give you a broader view of physics, and doing the 'pure' form will make you excel in one branch of physics.