The structure of nucleic acids, DNA and RNA, differ in that

a
RNA contains only three different nucleotides, while DNA contains four different nucleotides.
b
DNA contains a nucleotide with thymine, while RNA contains a nucleotide with uracil.
c
DNA's nucleotide sequence is single stranded, while RNA's nucleotide sequence is double stranded.
d
RNA's backbone is made up of phosphates, while DNA's backbone is made up of nitrates.

b

DNA contains a nucleotide with thymine, while RNA contains a nucleotide with uracil.