Wintergreen more upright and taller. Green Velvet rounder and denser.

I read that wintergreen grows wider than taller while Green Velvet is more rounded. Wintergreen also prefers partial shade to full sun so that may be a consideration for you too. I live in zone 6 and have Green Velvet boxwoods, which have really thrived in my landscape.

Maybe speak to the landscaper about longevity, how fast/large each grow, and their issues.

https://www.weekand.com/home-garden/article/green-velvet-boxwood-problems-18053690.php

This article comparing the two may also help. https://tnnursery.net/blogs/garden-blog/green-velvet-boxwood?utm_source=Pinterest&utm_medium=organic

I love the Green Velvet but agree Wintergreen could grow taller. Another one you might check into is Skylight, depending on your zone.

You might want to see if boxwood blight is in your area.

I second that thinkof129. Here in Northern Virginia, boxwood blight is a huge problem. It kills them and they look awful before they die.

My box topiaries were devoured by box moth. I got two ink berries, as often advised as a replacement, but do not consider them much like box other than having small evergreen leaves. Their habit is less neat and dense looking, their foliage isn't opposite and their growth rate is slower. I've been disappointed.

Check to see if boxwood blight is in your area is a problem. Happened to me and cost me a ton to replace hedges :(

IMO, Japanese holly, Ilex crenata, is a very suitable replacement for boxwood. Similar size, shaping and density, no blight issues or unpleasant aromas and fully evergreen. But both the box and the holly (alternating with the hydrangeas) are rather unimaginative landscaping choices.

I planted/replanted Ilex crenata var. Helleri in Zone 9. It died. Later learned that the area is not good for Japanese Holly. I have had good luck with Yaupon holly (Ilex vomitoria var. Stokes/Schilling dwarf). Low growing, mounding evergreen.