There are three main differences between DNA and RNA:
DNA contains deoxyribose sugar, RNA - ribose, which has an additional, compared to deoxyribose, hydroxyl group. This group increases the probability of hydrolysis of the molecule, that is, reduces the stability of the RNA molecule.
The nucleotide complementary to adenine in RNA is not thymine, as in DNA, but uracil is an unmethylated form of thymine.
DNA exists in the form of a double helix consisting of two separate molecules. RNA molecules are, on average, much shorter and predominantly single-stranded.
the structure of the nucleotide DNA and RNA has much in common. In particular, due to the similarity of nitrogen bases, information from DNA to RNA can be transferred according to the principle of complementarity, according to which not only nucleotides in the DNA-DNA system can form pairs, but also nucleotides in the DNA-RNA system.