Yes. Entirely different software. Different programming language and tech stack. Also different system requirements and feature set.
Not sure about the developer spirit. PieFed development has traditionally been moving crazy fast and it gets like several new features every month. I think that's a matter of focus. It comes with consequences, though. But I think overall the project is doing a good job with trying to be compatible to other software. Prioritizing important stuff and doing the right thing. Sometimes some things get done, rather than be 100% perfect. But past experience tells me things often get fixed or changed around once necessary. Not sure if that's a wise decision here. The JSON exchanged between the servers is probably extra work if changed around later.