Not the same location, except at Epcot.
At Epcot & AK, the distance is about the same as the buses.
At DHS, it's just slightly farther.
Cabs don't go all the way to MK, as the buses do. Instead, they drop at the TTC, where you'll need to ride the monorail or ferryboat to the MK entrance. Some people take a cab to the Contemporary Resort, from where you can walk to the MK, but it's about a half mile walk.