Fodder and hay are the same thing as far as I know. They are both cut dried grasses. Generally a mix of grasses it good. So it might say something like Prairie grasses, or native fodder. Other times it might have a particular grass listed, like Bermuda, or Timothy. If you can grow dark greens like spinach and kale, they can have those.
They can not go from a diet of all dried grasses to all fresh. You need to make diet changes slowly. But I give mine hay all the time, some pellets, and a small amount of fresh dark greens from my garden regularly.
Straw has had the nutritional stuff taken from it. They will eat on it, but it’s not actually feeding them. And I don’t think rabbits can have anything fermented, so silage is a no. I don’t know much about it, but if they are feeding straw and silage to cattle, the straw is just for fiber, the the silage had all the nutritional