Your tree looks like an ornamental Bradford (or Callery) pear. If we could see it in fully in bloom, and a close up of the leaf and flower, we could be certain. Originating from south-eastern China, Korea, Japan and Taiwan, the Bradford Pear has features very similar to the other ornamental pears. An upright shape, the tree has dark green glossy leaves with a color change in autumn. White blossoms appear in spring. As the tree matures the density, of the flowers increase, become more and more spectacular. Unfortunately, these are weak trees and will split easily in high winds or with heavy snow or ice. They are also becoming more and more prone to disease, and so are no longer as strongly recommended for use in landscape gardening.