@ObservedObject vs @EnvironmentObject

The roles of the two are very similar to each other. You can use one of them when you need to subscribe to a state object variable in a SwiftUI view.
The only difference between them is the way how they carry the object into subviews in terms of hierarchy.

☑️ @ObservedObject:

You need to pass the object as an initializing parameter through all the parent views after views till the last one where you want to subscribe the object in.
Imagine three views A, B, and C where C is one of the subviews of B, and B is one of the subviews of A. Then all A, B, and C will have to have @ObservedObject for the identical object even if A or B doesn’t need it.

☑️ @EnvironmentObject:

Unlike to above, you don’t need to pass the object through the parent views. You can use it anywhere you need regardless of hierarchy.

As such, @EnvironmentObject is much more useful than @ObservedObject in any case.
But why do you still need @ObservedObject?

References:
https://stackoverflow.com/questions/63343819/what-is-the-difference-between-environmentobject-and-observedobject
https://swiftwithmajid.com/2020/07/02/the-difference-between-stateobject-environmentobject-and-observedobject-in-swiftui/
https://www.hackingwithswift.com/quick-start/swiftui/whats-the-difference-between-observedobject-state-and-environmentobject