Title was a tad misleading.
Tarmac is a contraction of tar-macadam.
Which is a specific form of pavement created by starting with a compacted gravel base, laying a liquid "tar" (bituminous amalgam) over that, and finishing with a wear surface of gravel over that. That mixture is rolled together to fully cement the wear surface to the subgrade.
The color is based on the color of the wear surface gravel (whcih can be used for creative effect for driveways and the like). As the material weathers, the black tar may fade to a pale brown, to mid gray matrix about the surface gravel.
Tar-macadam is very similar to asphalt paving, except that, with asphalt the tar is melted and the the gravel (a finer grade) imersed in that tar base, and the resultant material laid in complete layers in a single pass.
It's color is nearly always a black or blue black to a deep, deep brown or black brown color. This can fade to a speckled gray as the tar is worn off the aggregate within.
Both of those pavements are poured in continous strips, and the edged melded together, leaving few, if any, seams. Such seams as exist, and all cracks are sealed with a flat black polymerized tar sealant.
Concrete takes its color from the Portland Cement used in it's mix. Portland cement--a kiln-heated lime product--is mixed with sand and gravel aggreate. The addition of water "activates" the adhesive nature of the Portland, which glues the stone and sand together.
As a constructed stone product, concrete is very strong in compression, but weaker in tension, whcih necessitates the used of steel reinforcement. It also recommends placing the concrete in explicit panels to maximize those stengths.
Those joints have sealant applied, to keep water out of the all-important subgrade. Those sealants can be white, cream, tan, or black in color. Concrete of certain eras and uses will have expansion joints of rot-resistant wood like cedar, teak, or redwood--thos invariably have a black sealant applied, and are very straight and true.
Concrete can be a very pure white, almost every shade of pale gray, both war mand cold gray.
To keep things interesting, for very heavy loads, it is not uncommon to use concrete as a sub-grade surface with either asphault or tar-macadam over that. Joints, especially expansion joints in the concrete below must needs be replicated i nthe asphaut or tarmac above.