Well, to the best of my knowledge; the question of which being 'easier' is the last one on anyone's mind related to the SLV program in any country. Although, conventional chain of thought and past experience has shown that most countries who have the ballistic missile technology with them find it easier to develop SLV tech because the former assists the latter.
Now, you can research and develop both the Ballistic Missile tech and SLV tech simultanously but separate from each other or have both programs share information and collaborate which makes it 'easier' (like in the case of Pakistan, the possible collaboration between Kahuta and Suparco).
Ballistic missiles (without warheads ofcourse) serve commonly as the first stage (and in some cases also the second stage) boosters to the SLV, giving it enough power to break-free from Earth's gravitational pull.
Cheers.
Note: Hope that suffices for now. If you need more information, PM me and I will see what I can get my hands on for you.