Sweet Potato as living mulch for peach seedling?

So I have been starting a bunch of trees from seeds.

Last year I started several apples, and pears and they are doing good. about 28 inches high.

This spring I got two peach pits to sprout, and I put them both on the top of two different swales, so that is one difference.

One of them was planted with sun flowers near it giving it some shade, which i thought a young tree might like.

the other one was getting full sun, and was growing through a mass of sweet potato vines.

Not only did the peach tree near the vines out grow the other peach by probably 24+ inches and several branches, this peach tree from pit out grow all of my other seedlings from apples and pears that were two years old.

SO my question is, do peach trees just grow fast, and the other seedling is a weakling? or do you think the vines really provide it that much more energy.

See attached photos

I wonder if the shade on the soil has kept the temperature at a level more conducive to growth. That and stable moisture might be the cause of your good fortune.

You're probably working with a number of different elements. Shade on the soil is one. The other thing to consider is whether the two trees came from different parents. I've had trees from the same parents grow entirely different, one a straight tree and one a bush form. The differences aren't usually as extreme as what you have here, but it can happen. I've had trees outgrow their siblings (half siblings?) by a foot or more. I've also had one die and one survive within feet of each other.

To test it, plant sweet potatoes around the other one next year. :)

Also in my experience apples and pears are MUCH slower growers than peaches. I have a four year old apple that's about three feet tall, and a 2nd year peach that's the same size. My 2nd year pears are still under a foot tall.