Interledger is a protocol that tries to unify all the different blockchain systems out there with a common interface, as well as provide a mechanism that the various assets can be moved and converted between them easily.
Hyperledger is the open source project of an actual blockchain, originally forked from Ethereum, and marketed to be used and instantiated as a "private blockchain" (I know I know) for organizations and corporations to make experiments with this concept.
Hyperledger was never forked from Ethereum.