Where the "social conservatives" tend to part ways with political conservatives is over the means. They're often too willing to adopt the liberal mantra of "big government does it better" and seek their solutions in further expansion of the federal government for things that should properly be left to the States.
Now this I absolutely agree with. I think you hit the nail squarely on the head and that would put me firmly in the political conservative column. I definitely do not believe the federal government needs to be the primary benefactor of society. It should perform it's role as it was intended, and leave most law, that does not affect interstate commerce or activity, to the states.