BIP39 stands for Bitcoin Improvement Proposal 39. The words are chosen from a particular list of 2048 common English words that may be used to the produce a binary seed (your non-public critical). BIP39 and 44, On the flip side, are a Newer method of standardization of a specific list https://growthbookmarks.com/story18761106/top-guidelines-of-bip39-word-list-pdf