While they are the same bullet... there is a slight difference. Because of the Lubalox coating the diam. on the BSTs is slightly larger, by about .0002-3". I know this isn't a lot, but it did make a difference in both accuracy and velocity out of my .25-06 AI. I really noticed it when seating bullets, it increased my neck tension, and I think that made a difference. With the C-T BST I got an extra 50-60fps vs. the Nosler BT and my groups went from 1.25" avg to about .850" avg at 200 yds . I've shot several 5 shot groups in the .3s at 100 yds. with the BST and never shot one under .6" with the standard BT.
Also, I noticed that all the BSTs I have measured are .015-25" longer than the standard BT, they engage the lands at 3.283" and the BT is in the lands at 3.268"... maybe it's just a fluke but I have measured a couple hundred of them.
I do know the 115s (in either format) hit WAY harder than the 100 grain BTs and absolutely hammer coyotes. ~JT