eg see https://github.com/ipfs/notes/issues/269
So you can't simply interop between the two without some sort of lookup to convert hash functions. It is hugely frustrating, as basically different content based distribution mechanisms cant work together.
In theory docker image registries support pluggable hash functions, although it is not clear to me that the ipfs function is even very well defined outside its own code. We could start to add a second hash calculation to every registry operation, but it would be a performance hit which some users would not like.
(tree based content hashes that allow parallelisation are nice, but the ipfs one is very ipfs specific and more complex than it needs to be I think).