Although at first glance the A4 & A5 appear externally similar,the A4 had improved engines- 1,340 hp Jumo 211J-1’s as opposed to 1,200 hp Jumo 211b,for the A5’s.

Armement varied but overall had increased over that of the A5-the rear part of the canopy had two gun rings instead of one & the gondola was improved.

Overall weight of the A4 was incresed through armour for the crew & greater bomb capacity.

A minor difference was the A4 had an extended rudder counter-balance.