SwiftUI: Difference between computed property and view as property

ContentView.swift

import SwiftUI

struct ContentView: View {

    @State private var name = "John"
    @State private var surename = "Connor"

    var motto1: some View {
        VStack {
            TextField("Enter your name", text: $name)
            Text("Hello, \(name)!")
        }.padding()
    }

/* Will not work with the following error
Cannot use instance member '$surename' within property initializer; property initializers run before 'self' is available
*/
//    var motto2 = VStack {
//        TextField("Enter your surename", text: $surename)
//        Text("I'll terminate you, \(surename)!")
//    }.padding()

    var body: some View {
        motto1
            .foregroundColor(.red)
//        motto2
//            .foregroundColor(.blue)
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}