A heel is the bottom, back part of a shoe or boot that provides elevation. The styling and construction of a heel may vary (i.e., stacked, stilletto, spiked, sculptured, kitten).
About Platform:
Platform describes footwear with raised, thick soles of at least one and a half inches in height. Platform soles are often made of cork, plastic, rubber or wood and are generally worn for fashion or to add height.