Can you go into detail about what separates the Endeavor from the Carrack as far as exploration is concerned? Why would I use an one instead of the other, and vice versa?

The Carrack is a dedicated explorer, built as a single, self-sustaining ship that can make long-duration voyages through the roughest areas of space. It's designed specifically for transiting jump points, dealing with terrible conditions in space and getting back home to tell the tale. The Endeavor's Explorer cab is more of an addon, something that can be separated and used should the need for exploration arise... but it lacks the range, the powerplant and room for addon equipment, the defensive systems and other elements that make the Carrack a tough, stand-alone ship.