Use transform|move from V vertex snap a to N nearest snap b. Nearest is an approximation snap unless you've got some other feature to latch on to. TC is a feature-based modeller, which means you use vertices, quadrants, intersections, mid- and divide points, tangents, centres to snap to and orient from, guides or construction lines are implicit. Snaps, including projections, opposite points, apparent intersections and so on are immensely powerful in feature-based modelling. TC's selector is a powerful transformation tool, but TC's assembly, transformation and copy tools give you ways to move objects that reference other objects and features in the drawing rather than the object you're actually moving. You can achieve the same things by moving the reference point around, but you don't have to, and other methods and tools have differences that can be useful.