Dilute HCl acid is stronger than highly concentrated acetic acid. Why?

HCl is a strong acid while, acetic acid is a weak acid. HCl acid ionises completely to $H^{+}\mathrm{and}{\mathrm{Cl}}^{-}$ ions. On the other hand, acetic acid dissociates partially. In an acetic acid, there is a large number of undissociated ${\mathrm{CH}}_3\mathrm{COOH}$ molecules, and just a few $H^{+}\mathrm{and}{\mathrm{CH}}_3{\mathrm{COO}}^{-}$ions. Hence, dilute HCl acid is stronger than highly concentrated acetic acid