RNA differs from DNA in 3 ways :
(i) The sugar phosphate backbone contains ribose rather than deoxyribose.
(ii) It contains the base uracil (U) instead of thymine.
(iii) It exists mostly as a single stranded rather than a double stranded helix.
Thymine is a pyrimidine present in DNA but not in RNA.
In deoxyribose sugar, hydrogen is present at 2 position.
Cytosine is pyrimidine present both in RNA and DNA.