Having asked a number of colleagues I failed to find a consistent answer to the question of the differences between SIGBUS and SIGSEGV. According to the Solaris signal(3head) man page we have:

     Name             Value   Default     Event
     ...
     SIGBUS           10      Core        Bus Error
     SIGSEGV          11      Core        Segmentation Fault

So I dug a bit further and found that siginfo_t can tell you more about the origins of the signal, in particular we have, from the siginfo.h(3head) man page:

     Signal         Code                 Reason
     _________________________________________________________________________
     ...
     _________________________________________________________________________
     SIGSEGV        SEGV_MAPERR          address not mapped to object
                    SEGV_ACCERR          invalid permissions for mapped object
     _________________________________________________________________________
     SIGBUS         BUS_ADRALN           invalid address alignment
                    BUS_ADRERR           non-existent physical address
                    BUS_OBJERR           object specific hardware error
     _________________________________________________________________________

Obviously this may be open to interpretation but that clarifies a few things for me.

For the techie take a look at the OpenSolaris source code for the trap() function. Here we see the handling for various types of trap including page faults. For example, there's a section where a decision is made as to return SIGBUS or SIGSEGV:

	case T_WIN_OVERFLOW + T_USER:	/* window overflow in ??? */
	case T_WIN_UNDERFLOW + T_USER:	/* window underflow in ??? */
	case T_SYS_RTT_PAGE + T_USER:	/* window underflow in user_rtt */
	case T_INSTR_MMU_MISS + T_USER:	/* user instruction mmu miss */
	case T_DATA_MMU_MISS + T_USER:	/* user data mmu miss */
	case T_DATA_PROT + T_USER:	/* user data protection fault */
		switch (type) {
        ...
		/*
		 * In the case where both pagefault and grow fail,
		 * set the code to the value provided by pagefault.
		 */
		(void) instr_size(rp, &addr, rw);
		bzero(&siginfo, sizeof (siginfo));
		siginfo.si_addr = addr;
		if (FC_CODE(res) == FC_OBJERR) {
			siginfo.si_errno = FC_ERRNO(res);
			if (siginfo.si_errno != EINTR) {
				siginfo.si_signo = SIGBUS;
				siginfo.si_code = BUS_OBJERR;
				fault = FLTACCESS;
			}
		} else { /* FC_NOMAP || FC_PROT */
			siginfo.si_signo = SIGSEGV;
			siginfo.si_code = (res == FC_NOMAP) ?
				SEGV_MAPERR : SEGV_ACCERR;
			fault = FLTBOUNDS;
		}

I was digging around this following a discussion regarding bug 6466257 (mmap file writing fails on nfs3 client with EMC nas device) and the signals delivered by mmap(2). The man page suggests that either SIGBUS or SIGSEGV can be returned for a number of error conditions but doesn't seem sure which. The answer is, "it depends".

So my conclusion is sadly another question - can an application developer infer anything from a SIGBUS versus a SIGSEGV? The answer, I believe, is yes - but quite often the result is the same which is to fix the code