The most different point is the composition of lecithin. Here are some numbers:
Peanut lecithin: PC=49%, PE=16%, PI=22%
Soybean lecithin: PC=21%, PE=22, PI=19%, PA=10%, PS=1%, Glycolipid=12%
This...
Soy lecithin is an emulsifier, it makes chocolate ingredients "well blended". For example, if you try and mix water and olive oil, you won't be able to do so: you will have oil blobs floating on top...