BIP39 stands for Bitcoin Improvement Proposal 39. The words are selected from a certain list of 2048 widespread English words which can be used to the make a binary seed (your private important). BIP39 and forty four, Alternatively, are a Newer method of standardization of a selected list of words https://webookmarks.com/story4370970/ledger-seed-phrase-bip39-no-further-a-mystery