Why do Hindus celebrate Holi and Diwali also what are the differences and similarities between Holi and Diwali?

Holi marks the end of winter and is known as the festival of colours, during which people cover themselves with coloured powder or water. It marks an even in Hindu tradidtion during which the good (in form of Prahlada) over evil (Holika, which was burn. Her ashes inspired people to use ashes in celebration, which later turned to colored powder.)

Diwali is the festival of light and marks the beginning of winter. It also signifies the triumph of good over evil. Historically, it marked the end of harvest.