The main structural difference between DNA and RNA are:
i) In DNA, sugar is deoxyribose while in RNA it is ribose sugar
ii) Piramidine base thymine is present in DNA only while uracil is present in RNA only.
iii) DNA exists as double strand helix where as RNA exists as a single strand. Functional difference between DNA and RNA is that DNA has the property of replication. DNA controls the transmission of hereditary characters. On the other hand, RNA controls the synthesis of proteins.