Truth is, I can't tell you what these are. They look like Sugar Maples, but with different characteristics. The yellow specimen above showcases a smaller leaf, with much denser distribution pattern in the leaves and brances. The one outside the Arkansas Capitol is still very much dressed (11/23/08) while the Sugar Maples in vicinity are mostly naked.
The Red variety (which might more aptly be called "Red Maple" showcases the Sugar Maple leaf, but appears to be a dwarfed ornamental hybrid.