Now Wikipedia and various other sources (teachers, textbooks etc) have led me to believe that when annihilation occurs, a particle and it's corresponding particle destroy each other, and subsequently release two or more photons.
Looks like this:
(kind of I made this on paint in like a minute).
Pair production, however, occurs whenever a photon (and here's where I get a little fuzzy) 'spontaneously' turns into a particle/antiparticle pair, provided it has sufficient energy and suchlike.
Now, as a photon technically has no anti-particle; it is it's own antiparticle, right?
Also; there is a theory somewhere, I'm sure, that states that as reaction work either way in space they must work in either direction in time (the proof Hawking used when he looked at black holes and reversed it for the big bang).
So surely it makes more sense that pair production is actually a photon-photon collision, as they are antiparticles and would annihilate each other, releasing particles/antiparticles as a result. This also makes kind of sense if you look at the Feynmann diagram(ish) for annihilation I drew above, and reverse the flow of time.
Long story short; is pair production a collision of photons rather than spontaneous decay?