For a proof that there's no difference in this specific case see Compiler Explorer
Both compile to the same code when optimizations are enabled.
static output.S.c.getter : Swift.Int:
push rbp
mov rbp, rsp
mov eax, 1234
pop rbp
ret
static output.S.d.getter : Swift.Int:
push rbp
mov rbp, rsp
mov eax, 1234
pop rbp
ret