Both Sycamore and Maple are from the same related group, so they're often tricky to tell apart. Sycamore tends to be a bit whiter (if it's dried properly) and tends to be a bit softer. I'll come at this from the other end of the problem and say the maker of these plaques would have been more likely to choose Sycamore rather than Maple...but they'd have been even more likely to have chosen Lime!