That is Viburnum macrocephalum, common name is Chinese Snowball. Zones 6-9, semi-deciduous- but mostly evergreen in my zone 8A climate. I've seen it reach 20' in height in less than 10 years from a 1 gallon plant. It's tough as nails, but initially resents being moved and doesn't start growing well for the first year or so. Don't confuse it with another viburnum, Japanese Snowball, which isn't nearly as showy. It's one of my favorites and always stops traffic when in full bloom in the spring. Flowers open a great apple green then turn pure white. There is a second, less showy fall bloom as well. In my experience it essentially free from pests and diseases and only requires some aggressive pruning to control it's somewhat gangly form as it quickly grows from a shrub to a small tree. Prune it as a multi-trunk small tree and keep the lower limbs free from wild sprouts for best effect.

Beautiful! I'm ordering one today! :D