1. WM

   White matter is made up of the neuronal axons that connect neurons in the "gray matter" brain regions. White matter also helps the regions of the brain to communicate with one another.

   White matter primarily sits below the cortical layers, and in tracts connecting different brain areas
   

2. GM

http://www.indiana.edu/~p1013447/dictionary/greywhit.htm

The CNS has two kinds of tissue: grey matter and white matter, Grey matter, which has a pinkish-grey color in the living brain, contains the cell bodies, dendrites and axon terminals of neurons, so it is where all synapses are. White matter is made of axons connecting different parts of grey matter to each other.

The grey area in Figure 1 shows the location of grey matter in the middle of the spinal cord and the white matter surrounding it. 

The pink areas in Figure 2 show the grey matter of the cerebral cortex on the outer surface of the cerebral hemispheres. The grey areas show grey matter inside the hemispheres and in the front end of the brain stem.