From Serious Eats comes the Pizza Cognition Theory which stems from how people learn what something is — which is that they first must learn what that thing is *not*:
The first slice of pizza a child sees and tastes (and somehow appreciates on something more than a childlike, mmmgoood, thanks-mom level), becomes, for him, pizza. He relegates all subsequent slices, if they are different in some manner from that first triangle of dough and cheese and tomato and oil and herbs and spices, to a status that we can characterize asÂ not pizza.
What you first recognize as Pizza will forever be Pizza to you, everything else will be “not pizza” or “another kind of pizza”. Â For me (for better or worse) it’s the Little Caesar’s standard pizza. Â Everything else substantially different gets described with a qualifier (i.e. Buddy’s pizza).