Kind of sort of mostly? The big difference here is that Bcachefs is a filesystem based originally on the design of Bcache which is a block device caching layer

Kind of sort of mostly? The big difference here is that Bcachefs is a filesystem based originally on the design of Bcache which is a block device caching layer, so it'd be very easy to miss the fs on the end and confuse Bcachefs for Bcache. Because of this, calling it Bcache filesystem also doesn't really work because it's not Bcache anymore either.