Answer
Aluminium nitride: $AlN$
Aluminium nitrite: $Al (NO_{2})_{3}$
Work Step by Step
The presence of -ide in nitride means its a monoatomic anion. Aluminium has a +3 charge, and nitride has a -3 charge. The charges are balanced, therefore the chemical formula for Aluminium nitride is $AlN$.
The presence of -ite in nitrite means its a polyatomic anion, containing oxygen. Nitrite ion is $NO_{2^{-}}$, Thus in order to balance, three atoms of nitrite ions should be present. Thus, $Al (NO_{2})_{3}$
