DNA and RNA are both

DNA and RNA both contain pentose sugars.

DNA and RNA are made up of monomers called nucleotides.

DNA has a nitrogenous base called Thymine, but RNA doesn't. Instead, RNA has Uracil. In DNA thymine pairs with adenine, but in RNA uracil pairs with adenine.

In evolved in the system of DNA synthesis wich means DNA and RNA both work to gather in what is called DNA replication wich resulting the replication of NEW DNA strands.