PE stands for Potential Energy. It is the stored energy in an object due to its position with respect to some reference. It is expressed in Joules.
P.E = m * g * h OR P.E. = mgh
m - mass of the body
g - acceleration due to gravity
h - height attained due to the body's displacement.
K.E. stands for Kinetic Energy. It is the energy possessed by a body due to its motion.
K.E = 1/2 mv² where m = mass of the body; v = velocity with which the body is moving.