I solve the difference in both using preview code:
#Preview(windowStyle: .automatic, traits: .fixedLayout(width: 1280, height: 720, depth: 540)) {
HomeScreen()
}
and for App screen size
@main
struct MyApp: App {
var body: some Scene {
WindowGroup {
HomeScreen()
}.windowStyle(.plain).defaultSize(width: 1280, height: 720, depth: 540)
}