Is there a document giving the major difference between Hubzilla and Zap?
Hubzilla is a decentralised content management system developed mostly between 2012-2015 (before ActivityPub was even a thing). It uses XML-based ActivitystreamsV1 for object storage and traditional Zot as primary transport.
Zap is a social networking app from 2019-2020 and uses ActivityStreams JSON-LD for object storage and Zot6 as primary transport.
These are the major reasons the two applications aren't directly compatible. They both evolved from the same code repository, but migrating between the two is sort of like trying to mate a butterfly and a cobra. They aren't the same species and have evolved independently in completely different evolutionary environments.
