They are the same: asm! was replaced by llvm_asm! because it currently only supports llvm asm and the name might suggest otherwise [1]. A backend independant syntax for asm! was recently specified [2], but that will take some time to implement.
That first PR moved the old asm to llvm_asm, and then the new asm was built after a period of time so folks could migrate their code to llvm_asm, as a temporary measure. This commit happened after that transition so this has to be from the new asm back to the transition version.