1. difference between white matter and grey matter?

 White matter is one of the two components of the central nervous system and consists mostly of myelinated axons.

White matter appears white due to the presence of large amounts of myelin, a fatty protein that serves an insulation function for signal transmission.

Nerve impulse travels faster due to presence of myelin sheath in it. 

Grey matter  is a major component of the central nervous system, consisting of neuronal cell bodies, neuropil (dendrites and both unmyelinated axons and myelinated axons), glial cells (astroglia and oligodendrocytes) and capillaries

 Grey matter appears grey-brown due to the presence of neuronal cell bodies and capillaries, as well as the relative lack of myelin.

Nerve impulse travels slow due to lack of myelinated neurons in it