My grandfather was very well known for his orchard. There was one apple tree that had 3 different kinds of apples on it, as a result of grafting. I've never tried it myself, but took a Master Gardeners class and we had a session on starting fruit trees from rootstock.
You should come to my area and I can show you whole orchards that were once one kind of apple and are now another kind after they took the trees down to the stump and grafted on another variety. They got it down to a science .
You can grow a tree from a cutting, but it's rarely done. Each variety grows in a different size and shape. By grafting the variety you want onto a know root stock, you get to choose both the variety of apple, as well as the size and shape it grows in.
As a young man, my brother and I used to t-bud (nobody serious grafts anymore) about 1,000 trees per day for most of June. We not rarely were part of a 10 crew team. It was a pretty good business until the EU expanded and the low wage countries took over the business.
What variety's of trees can an apple be grafted with? Willow?
I’ve never done anything but apple on apple, pear on pear, and plum on plum. You can graft apple on crab apple, nectarines on plums and grapefruit on orange, IIRC, but you have to stay within the genus to be successful.