They are all saplings from 4 to about 10 foot tall.
My yard is mostly 100 foot pines, a few sweetgums, and a large oak. But I have some bare spots that get cooked by the sun. I put some fat growers there.
Those maples grow fast. The red oaks are also fast but not as fast as the maples and they live longer. The live oaks are slow, but they live for a very long time.
In bare spots, I like to put fast growers and slow growers near each other. That way, by the time the fast growers dies, the slow grower will be a decent size.