How many different varieties of 'pancake' are there?
I'm not going to accept this as an answer, but as Community has decided to give it a nudge.

I wrote up my little 'experiment' after I did it.

Although culinarily, a pancake would be something from a batter that is self-leveling, there seem to be a few other categories that many people may not consider 'pancakes' based on their upbringing :


Items made from shredded vegetables, with starch or an egg as a binder : latkes (Jewish; aka 'potato pancakes'), okonomiyaki (Japan), jeon (Korea), kartoffelpuffer (Germany)
Dough that is rolled out very thin and then cooked on a griddle or in a pan: roti (India), some varieties of bing (China, eg. 'scallion pancakes' (cong you bing) and 'mandarin pancakes' (bao bing)).  Note that this would also include South American tortillas and many flatbreads.  (although not classic preparations of naan (India) which is made in a tandoor)
Batter or gruel that is spread out, rather than self-leveling: crêpes (France), dosa (India), matafan (France), some styles of jonnycakes (USA), some styles of hoecakes (USA)


For the self-leveling batter-based pancakes, we can still divide them up into a few categories, as not everyone considered all of them pancakes:


large, thin, and unleavened: pancakes (England), pannekoeken (Netherlands), pannkakor (Sweden), pannekaken (Norway), pfannkuchen (Germany)
Leavened, cooked in a depression (not a flat griddle or pan), may be rotated during cooking: poffertjes (Netherlands), æbleskiver (Denmark), takoyaki (Japan)
Unleavened (other than whipped air &amp; steam) cooked in a vessel in the oven: Dutch babies (USA), pannukakku (Finland), Yorkshire pudding (England).  May include other popovers.
Leavened, cooked on a pan or griddle: drop scone (UK), pancakes (USA; aka flapjacks, griddlecakes), pancakes (Scotland; aka 'Scotch pancake'), pikelet (Australia), some styles of jonnycakes (USA), some styles of hoecakes (USA)


I'm not sure how to classify the following:


injera (Ethiopia); might be self-leveling, but is poured in a spiral (so either pancake variety 4 or non-pancake variety 3).  Also not flipped, which is abnormal for griddle-cooked pancakes.
kanom krok (Thailand); cooked in a depression like pancake variety 3, but assembled like a sandwich rather than being individually flipped.
kaiserschmarrn (Austria); either mixed during cooking or cut up after making a pancake of variety 4.