Answer: Ernest Wilson is a named variety of mimosa, it was selected because it is exceptionally cold tolerant and can be grown in colder areas than many mimosas. In your area, this would not be of particular concern as mimosas are fully hardy for you. So either one would grow in your area.
Mimosa trees (Albizia julibrissin) need full sun preferably all day to grow their best, so I am not sure your location will be sunny enough. These trees are unfortunately subject to vascular wilt problems as well as insects; and, they do naturally drop their seed pods and foliage in the fall. And transplanting from one planting spot to another is problematic due to their root system. So I am not sure this is the best choice for you.
Monrovia is a wholesale-only nursery. You might check with your local retailers that carry Monrovia (and other) products and see if they can help you analyze the growing conditions where you want to plant and help you select something that will thrive there and also meet your design goals. Enjoy your new tree!
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