$\mathrm{HCl}$ gas is covalent and $\mathrm{NaCl}$ is an ionic compound. This is because

Electronegativity difference between $\mathrm{H}$ and $\mathrm{Cl}$ is less than 2.1

Sodium is highly electo +Ve
 

Hydrogen is a non-metal
 

$\mathrm{HCl}$ is a gas.