Actually, what akvadrako described is just called multiprocessing - not SMP.
SMP refers specifically to systems with uniform latency to shared memory. So any distributed memory topology like ccNUMA w/ interconnect would not fit that definition.
"No, that's SMP" - is perhaps too resolute a definition. I'd say SMP is across processes, SMT is within a process, which would put the distinction in software, not hardware architecture.
Definitions are more grey, muddy and dependent on context; in that line of thought, I feel the parent you're responding to is accurate enough to not warrant criticism or even downvotes.
No, these things are really quite clearly defined, and certainly not so muddy to include something like "which would put the distinction in software, not hardware architecture.". These are hardware architecture terms.
