When to use @Input and when not in angular2

I Am new to angular2. Trying to understand the usage of @Input in a better way. We can pass values from parent component to child using @Input also we can create a service variable and inject it to the parent component and can access them in child components. Which way would be better? I am getting these values through route resolves. I am feeling skeptical to use @Input when there is no binding of it with user input.