Trees are available in different forms for planting purposes. The most common are: bare root, container grown, and balled-and-burlapped.
Bare root: common with mail-order fruit trees. They will be relatively small and the roots will not have soil around them. They are shipped late in the winter for early spring planting. These tend to do very well, as the bare root package leads to great root-to-native-soil contact, a very important thing. Being small, they tend to establish easily and grow quickly.
Container grown: common in local nursery stock. These trees have lived their entire lives growing in containers of different sizes. It is common for these trees to have circling roots due to the size limitations of the container system. These circling roots need to be cut at a point before the circling starts; new growth from the cut surface will grow out away from the trunk, as it should.
Balled-and-burlapped (B&B): Most larger specimens will have this type of root package; it is what the City of Albuquerque typically plants, due to our need for larger initial size. These trees are heavy, a few hundred pounds usually, and should be handled and planted by professionals. While they provide a quicker initial presence, they usually take so much longer to establish and begin strong growth that a smaller specimen will overtake and surpass them within a decade or so.