1. Sugar: RNA contains ribose sugar, while DNA contains deoxyribose sugar. The difference lies in the presence of a hydroxyl group (-OH) on the 2' carbon of ribose, which is absent in deoxyribose. This makes RNA less stable than DNA, as the hydroxyl group is more reactive.

2. Nitrogenous Bases: Both RNA and DNA use adenine (A), guanine (G), and cytosine (C), but RNA uses uracil (U) instead of thymine (T), which is found in DNA. Uracil, like thymine, pairs with adenine.