Took at quick look at apache nifi. Here is my conclusion but anyone feel free to correct me if I am wrong:

I think they only overlap for a small part but quite different:

* Nifi is focusing on moving/sharing datafile (meaning the size could be big) across the system * Nifi does have some logic control flow to act like workflow, but it's not too closed to be a "workflow system" because it missing a lot of capabilities that a typical workflows should have (see "What they all have in common " in https://medium.com/@qlong/iwf-vs-other-general-purposed-work...)

* iWF is a general purposed workflow engine, could conceptually do data sharing but it is not good at sharing the big amount of data or data files * iWF is more specialized at controlling/orchestrating the business