Evan, maybe "Patio/Ornamental/Small Tree" is used more in the South. It could be a container plant or in ground, like Brugmansia (Angel Trumpet) or some citrus here in 9b. It's the size and function rather than where it's planted that makes it that category.
Typically, it's a tree (or shrub trained to 1-2 trunks) no more than 10'-12' that could be incorporated into a border (or on the patio) without overwhelming other plants, or be a focal point for mixed plantings. To try to put it in more Northern terms, my friend in Minnesota has the dwarf ornamental crab apple 'Cinderella' - it's very slow growing and reaches maybe 8' at maturity with a little dense rounded crown. It's the centerpiece of that bed with other shrubs and perennials supporting the design (doesn't that sound la-de-dah). That would be an example of the category. You might use a dwaf-ish conifer in the same way, like Thuja 'DeGroot's Spire'. On the other hand, Thuja 'Green Giant' wouldn't fit.
Here's an example of Brugmansia (a Patio/Ornamental/Small Tree). Notice that it doesn't terribly shade other plants, nor be out of proportion (I hope)
The more I explain, the more confusing it sounds! But does that help at all?
Monica
