What's the difference between thin crust pizza and a cracker
Two factors:
Leavening: pizza crust is generally made with a leavened, yeasted dough, that has risen for a hour or more before rolling out.  Crackers are generally made with a &quot;short&quot; dough, which contains no leavening at all or only a tiny amount of chemical leavening.  Even crackers that are made with a yeasted dough (e.g. sourdough crackers) are not given a long time to rise.
Texture: crackers are generally supposed to, well, crack.  They should be crisp, crunchy, and/or flaky.  Whereas pizza dough is supposed to be chewy and/or bready, and certainly not crunchy.
Now, there's obviously some room for overlap here.  For example, if I roll out a sourdough pizza crust really thin and top it only with salt, and bake it until crunchy, it's not going to be particularly different from a sourdough cracker.  However, most pizza crusts are very different from most crackers.
Hope that helps!