Code is based up LoRaMac-node … Heavily modified though. But I guess that does not matter that much. All of the functionality is wrapped into a nice and way more useful Arduino Class. Lot’s of examples how to use things. Here the link to the include file to show the API (sorry, I am notoriously bad about writing docs):
Guess from a technical point of view this core is written from scratch, low power and high performance in mind, and compatibility with the “Arduino SAMD Core”. The other code you referring to is WI6Lab’s attempt to come up with something generic ontop of ST’s HAL.