Purple Plum - one of the many "purple"-foliage cultivars of Prunus cerasifera. It'll be a lot less beautiful when the flowers are finished, more a rather dingy blackish-brown than purple, all of the summer. The leaves also often get badly chewed up by aphids and look horrible. The plums are edible though, so it isn't entirely a waste of space. PS why was I thinking this would be a question about trees in New York?? ;-)
Leaf coloring varies with cultivar and site. It being Vancouver these were probably planted as 'Nigra'. Superficially similar stock traded down here as 'Thundercloud' and 'Krauter's Vesuvius'. The latter was selected in California for remaining quite dark in hot weather, unlike plants grown as 'Thundercloud' which may become coppery. Both are nearly interchangeable in spring. The stronger pink flower as seen here is associated with the more deeply colored foliage. Another common one on the market here as 'Pissardii' produces light pink, nearly white flowers. It is not certain the original 'Thundercloud' of L. Burbank is still in commerce. 'Pissardii' was introduced a long time ago and may have been replaced or supplemented by multiple independent introductions since. Even comparatively recent 'Thundercloud' may have become muddled due to people grafting from say, purple-leaved seedlings found growing spontaneously and put on the market under a popular cultivar name ('Thundercloud', in this case).