Furan and pyrrole are both heterocyclic aromatic compounds containing a five-membered ring. The primary difference between them lies in the heteroatom present in the ring and its contribution to the aromaticity.Furan contains an oxygen atom as the heteroatom, while pyrrole contains a nitrogen atom. In terms of aromaticity, both furan and pyrrole are aromatic compounds due to the presence of 4n+2 where n is an integer electrons in their conjugated systems, which satisfy Hückel's rule.In furan, the oxygen atom contributes one lone pair of electrons to the system, making a total of 6 electrons 4 from the carbon atoms and 2 from the oxygen atom . In pyrrole, the nitrogen atom also contributes one lone pair of electrons to the system, resulting in a total of 6 electrons 4 from the carbon atoms and 2 from the nitrogen atom .The difference in the heteroatoms affects their chemical reactivity. In furan, the oxygen atom is more electronegative than the nitrogen atom in pyrrole. This results in a higher electron density around the oxygen atom, making furan more susceptible to electrophilic aromatic substitution reactions at the positions adjacent to the oxygen atom C2 and C5 positions . Furan is also more reactive towards electrophiles due to the presence of the oxygen atom, which can stabilize the positive charge in the intermediate formed during the reaction.In contrast, pyrrole is less reactive towards electrophilic aromatic substitution reactions due to the lower electronegativity of the nitrogen atom. However, pyrrole is more nucleophilic than furan, as the lone pair on the nitrogen atom is more readily available for donation. This makes pyrrole more reactive towards nucleophilic aromatic substitution reactions.In summary, the primary difference between furan and pyrrole in terms of their aromaticity lies in the heteroatom present in the ring oxygen in furan and nitrogen in pyrrole . This difference affects their chemical reactivity, with furan being more susceptible to electrophilic aromatic substitution reactions and pyrrole being more reactive towards nucleophilic aromatic substitution reactions.