A comparative study on BN and AlN substitution patterns in C-60 fullerene and the chemical and electronic properties of these substitutionally doped heterofullerenes has been carried out using semiempirical (MNDO and PM3) and density functional (B3LYP) theories. Several basis sets, namely, 3-21G, 3-21G*, and 6-31G*, are used. Specific systems considered here are C60-2x(BN/AlN), where x varies from I to 3. Both similarities and dissimilarities have been noticed in the substitution patterns between BN- and AlN-fullerenes. Some of the rules already established in BN substitution patterns are followed by its AlN counterpart. For example, like BN, AlN units prefer to stay together. However, the prominent "hexagon filling rule" of BN-fullerenes is disobeyed by AlN. Its larger atomic size and the weak nature of the Al-N and Al-C pi-interaction may be the reason for such discrepancies. AlN substitution causes much more distortion of total electron density Of C-60 than its BN counterpart, making the fullerene easier to oxidize and reduce. The HOMO-LUMO gap (band gap) strongly depends on the number of substituent units, and the changes are minimal for the BN system in comparison to its compeer. Finally, the possibility of dimer formation of BN- and AlN-fullerenes has been studied.