It is ... and it isn't. Your linked source is American, and Americans use the term Sycamore maple simply to distinguish Acer pseudoplatanus (European sycamore) from American Sycamore (Platanus occidentalis), which, as you can see is not a maple (Acer) at all. What the Americans call sycamore has a living appearance similar to maples (such as European sycamore and American maples) but if looked at carefully it's physically more similar to London plane: this isn't a surprise because one half of the genetic background to London plane is thought likely to be American sycamore. The wood of American sycamore isn't really very maple like, and is closer to matching characteristics found in London plane, which isn't really a surprise.Apparently it is!
This wood and tree species identification thing, I admit, can get very involved and nit-picky, but it's usually interesting, and sometimes frustrating ha, ha. Slainte.