I think I’ve explained this to you in a PM before.
Basically, Connect is over a local network - you must have a device running Infinite Flight nearby on the same network in order to interact. As a result, you can control almost everything IF related from an interface on that network.
In contrast, the Live API (RESTful API) is accessible over the internet. This is only for retrieving data, such as aircraft positions, etc.
For you, you’d be after the Live API to have your app available as a website. If you were to use the Connect API on the web, you’d probably have to package it as a Chrome extension or something to get it to work, probably not the best thing for a beginner to do.