Aside from style, the only difference between Ted Cruz and Rand Paul is on foreign policy. Ted Cruz has not yet opened his eyes to the perils of nation building.
But their current strategies are very different. Paul is communicating to a larger audience: the entire country. His goal is to win the general election.
Cruz, on the other hand, is focused on throwing red meat to the base, again and again. This keeps the base happy but will not carry him very far in the polls. His purpose is to fill in the VP spot. He all but endorsed Rand Paul already. I can post the youtube videos if you want.