Both buildings were designed by Ernest Flagg, a Beaux-Arts trained architect. and the latter was completed in 1908. The Little Singer Building is an L-shaped building, with two similar facades. The one pictured above is on Prince Street, and is slightly more narrow than the one on Broadway. It combines large glass panes, terra-cotta panels, and wrought-iron balconies to create its ornate facade.
Today, apparently, it is a mixed-use co-op. I love that they've kept the facades intact. For more photos and history, check out NYC Architecture. And, if you're looking to buy an apartment, there's a 2 bedroom for sale in there!