I found this web page with side by side comparison of common maple species. It's not a complete list but maybe interesting or helpful for some. It covers mostly the species you might find commonly growing in parks, but nothing exotic. The photos are organized in a way that makes it easy to compares leaf shape, buds, and samaras. Maples in Order by Specie Hort 231: Comparisons of maple leaves, buds, and fruit (samaras) Maples in Order by Plant Part Hort 231: Comparisons of maple leaves, buds, and fruit (samaras) I included two screen shots for those that are concerned about clicking on links.
