architectural differences between iplug 2 and JUCE for standalones?

[hibrasil]

From what i've heard about your project, i am not sure why you would base it around iPlug2 which is a plug-in focused framework, and in terms of standalone app only really offers you cross platform audio/midi abstractions and single window UI, with a UI toolkit that is designed for the kind of controls you get in plug-ins.

JUCE is a more fully featured, audio-focused application framework that also does plugins, and has a lot of functionality that will save you time. JUCE uses the observer pattern quite heavily for the UI and I think the scalability that it offers would probably be more appropriate than what you get in iPlug2. I use JUCE to build my app pMix2. If you can live with the license stuff I don't think you would regret it.

I'd also consider using Electron, which can make some really slick apps. Also React Native, Flutter are now supporting desktop and might be interesting.