Originally Posted by
tspek
Technically, no...it's not the number of teeth that changes the effect of chainrings/cogs, it's the diameter. However, the number of teeth change that diameter.
Right. Otherwise V-belt drives wouldn't work because they don't have any teeth.
Smaller pitch means that an increase of one tooth gives a smaller increase in diameter than an increase in one tooth of regular pitch so you get smaller jumps between gears. You also get the ability to wrap around smaller diameters but there are other factors limiting that as well.