Statement-1: ${\mathrm{NO}}_3^{-}$ and ${\mathrm{PO}}_3^{-}$ have similar formula type but differ structurally, i.e., they have different type of hybridization. 

Statement-2: ${\mathrm{NO}}_3^{-}$ ion exists as free ion. On the other hand ${\mathrm{PO}}_3^{-}$ exists as cyclic or linear polymeric structure.

${\mathrm{NO}}_3^{-}$ and ${\mathrm{PO}}_3^{-}$  have different type of hybridization. Because there is one centre atom in nitrate, which is surrounded by three similarly bound oxygen atoms that are located at the corners of a triangle and on the same one-dimensional plane. Nitrate contains three electron domains and no lone pairs.

The ${\mathrm{PO}}_3^{-}$ ion has one double bond and two single bonds between the Phosphorous (P) and Oxygen (O) atoms. The Phosphorus atom (P) lies at the middle, surrounded by three Oxygen atoms (O).