Sincere question gets a sincere response.
The differences. First xiaolongbao lit. small basket buns. These are a specialty of HUaiyang cuisine, sometimes called Shanghai cuisine here, sometimes called Jiangsu and Zhejiang cuisine(s) in China. the dough is thin and kneaded like a western wheaten dough. The filling is usually pork. There can be bits of crab mixed in - a variant of this type of dumpling uses just crab eggs/ovaries and is considered the gourmet's dream in China for this kind of cooking.
There are many varieties of bao(zi) served in this region, and Shanghai is particularly famous for them, like NY for pizza or New Orleans for muffalettas(sp?).
The xiaolongbao (which ARE also called XL tang bao xiaolong soup rolls) have a little secret. Once the filling is placed on the dough, a bit of gelatinous soup, like the French make, is placed atop the fillingand then the dumpling is sealed, twisted and decoratively marked. Then it's steamed in the basket.
Carefully lift them when served (wait a minute or two, they will scald if you lift them right away) using a spoon and chopsticks, dip and eat all at once so you get the reconstituted soup now enriched with the juices of the filling. SUpposedly, these xlb originally come from Ningbo, SE of SHanghai. At DinTaiFung, there are many varieties of baozi and jiaozi (different kind of bun). In Shanghai, some bao are quite large, none are like the har gao or charsiubao in the fluffy dough balls you see at Cantonese yumcha/dimsum houses. If you want xlb anywhere, try saying this in Chinese (syiaou loong bao) it's close.
Potstickers. Different cuisine. Classically(I"ve been told) these are from the north, shandong and adjacent areas incl beijing. CHinese name Guo Tieh(r). Guo is mandarin for wok, tieh means sticking to the side. These are made similarly to the northern jiaozi, these are the dumplings either boiled or steamed usually filled with pork and chopped cabbage or fish and chopped cabbage that you'd find at say, mandarin deli, dipped into soy and vinegar (preferably zhenjiang black vinegar) with maybe a bit of ginger. The best guotieh are the ones where the dough for the dumplings is freshly made and where the dough is still a bit damp so that when they fry, the "potstickers" actually stick a bit to each other and can come to the table with a thin skin connecting them that you break apart. Deerfield Garden sometimes makes them this way as did the late Quanjude. I think China Islamic makes them but with lamb.
Every Chinese cuisine and most east asian cuisines have filled pasta of some kind, mandu in Korea, Morangak here has them with pheasant meat. But there are differences between the regions, no one but Sichuanese make chaoshour (fried "hands") small wonton like dumplings (like pelmeni) that are then tossed in a hot chili, vinegar and szechwan peppercorn flavored sauce.