Both DNA and RNA are made up of nucleotides, which are the monomers of nucleic acids. Each nucleotide consists of three components:

* A sugar:

* Deoxyribose in DNA

* Ribose in RNA

* A phosphate group: This is the same in both DNA and RNA.

* A nitrogenous base: These differ between DNA and RNA:

* DNA: Adenine (A), Thymine (T), Guanine (G), Cytosine (C)

* RNA: Adenine (A), Uracil (U), Guanine (G), Cytosine (C)

So, while the sugar and phosphate groups are similar, the key difference between DNA and RNA lies in their nitrogenous bases.