The only thing that varies from one nucleotide to another in DNA is the nitrogenous base.

Here's a breakdown:

* Nucleotides are the building blocks of DNA.

* Each nucleotide consists of three parts:

* A sugar molecule (deoxyribose)

* A phosphate group

* A nitrogenous base

* The sugar and phosphate groups are identical in all nucleotides.

* The nitrogenous base is what distinguishes one nucleotide from another. There are four types of bases in DNA:

* Adenine (A)

* Thymine (T)

* Guanine (G)

* Cytosine (C)

The specific sequence of these bases along the DNA molecule forms the genetic code that determines an organism's traits.