Both pieces are "normal". Sycamore, like most all hardwoods has a dark heart wood and a lighter sapwood. The heart wood can be in a variety of shades as can the sap wood as well as mixed in a single board. We have three species of wood traded as Sycamore or lacewood in North America. American Sycamore indigenous to the east, but shade and street trees thru out the country; California Sycamore from... and London Plane, indigenous to Europe and the UK with shade and street trees in this country. Plane heart wood is most often darker in general. Most of the cluster burl sycamore slabs in my warehouse are 6/4 and 8/4 London Plane species from which I cut the best pieces and dye them....takes dye beautiful and is the best way to bring out the ray fleck figure. Unfortunately, the burl pips or knots in sycamore tend to open up if dried to fast. The quarter sawn instrument wood is American Sycamore. Sycamore timber is very unstable unless quarter sawn and dried properly.
Burl Source, you said you pulled that chunk out of the brush...must need some drying yet? What's the moisture content?