White flowering trees
These are, indeed, Bradford pear trees (Pyrus calleryana 'Bradford) and they are, indeed, invasive trees. Originally introduced for their beautiful shape and spring blossoms,, it soon became obvious that the branching system was unstable in high winds and the brittle nature of the wood resulted in frequent damage to the trees and surrounding structures, etc. Birds love the small, otherwise inedible fruit, and plant the trees in numerous places where they then proceed to choke out any native vegetation that may be in the area.
They are becoming a major problem.