Strength refers to the ability of the acid to lose hydrogen ions and therefore its concentration of hydrogen ions. A strong acid dissociates completely to form hydrogen ions. A weak acid dissociates partially to form hydrogen acid. On the pH scale strong and weak acids and bases are categorized. 1-3 is strong acid and 4-6 is a weak acid. 8-10 is weak base and 11-14 is a strong base.
Concentration
Concentration refers the amount of acid or base present in a given amount of solution. Amount of acid or base per liter. Concentration in our case is the moles of a base or acid. For all substances concentration is the the abundance of the constituent divided by the volume of the mixture.