Which nucleotide differs in RNA compared to DNA?

In RNA, the nucleotide uridine is present instead of thymidine, which is found in DNA. This is the distinguishing feature between DNA and RNA. While adenine, cytosine, and guanine are common to both nucleic acids, thymidine is specific to DNA. Uridine serves the same purpose as thymidine in that it pairs with adenine during RNA synthesis. The presence of uridine, which contains a hydroxyl group at the 2' carbon of the ribose sugar, reflects the structural differences between RNA and DNA. Thus, uridine is the correct nucleotide that differs in composition when comparing RNA to DNA.