Widewing will probably have the correct answer but I'd say the differnce is "lack of F3 view"
F3 view even during ground attack is far superior to cockpit view!
JUGgler
Absolutely agree. F3 Allows you to see far better than any of the types Karnak listed. Granted, the very short vehicle icon range makes a big difference over what it used to be, but the advantage still means you don't have to bank left and right to watch for tell tale signs of enemy GVs.
A second advantage is eight 500 pound bombs... That's 8 opportunities to kill vehicles. 8 bombs on a town, etc. No fighter can kill as much armor as effectively in a single sortie, and we still have to consider the six .50 caliber MGs packed tightly into the nose. One quick pass will kill most lightly armored vehicles, largely due to the concentration of firepower.
The third advantage is the that the A-20 excels at dive bombing, due to outstanding low speed handling and virtually no nose bounce.
Let's compare the A-20 to other medium bombers...
Boston: An earlier version of Havoc (A-20C). Very similar speed and climb, actually turns better than the A-20. Carries only 4 bombs and has much lower forward firepower (four .303 MGs in nose). The Boston has fabric control surfaces, which are much less effective at speeds above 225 mph. To get a Boston turning at speeds above that, you will need to add a lot of up elevator trim. Juggler knows what I'm speaking about, he was one of those who liked to go dogfighting in the Boston.
B-25: Much heavier than the A-20. The C model is the more agile. Good bomb load and forward firepower, but the limited maneuverability, much less speed and climb make it far less survivable in a fighter-rich environment.
Ju 88: Good bomb load, decent agility. Much slower than the A-20, and pathetic climb in comparison. Nearly worthless firepower forward. An A-20 will literally fly circles around the Ju 88.
All of the above have the F3 option. All have multi-man aircrews. The A-20G has a 3 man crew, pilot and two gunners (the ventral gun is missing in the AH A-20 as they had no photos on which to model it at the time). The Boston has a four man crew. Both the B-25s and Ju-88 have four or more crew members. The A-20 is not afforded anything other bombers don't have. All bombers, single engine, twin engine and four engine have the F3 option, essential for any chance at survival in the MA. A lone pilot cannot effectively man a bomber without F3.
The IL-2 lost that option because was not being used nearly as much for ground attack as for field defense as a fighter against fighters. The 23mm cannons are extremely effective against aircraft, relying on the F3 view to pray and spray. You can still use it as a fighter, but now you are limited to using the gunner's position to see behind, which you can key-map or map to a joystick switch. The problem is that as soon as you switch to the gunner position, you lose the ability to maneuver. I disagree with this last change, feeling that limiting forward gun use to the cockpit view only would have been enough to limit the Stormovik scourge. I believe that the best solution is this: No forward shooting or bomb release if in F3 view. That will eliminate much of the gaminess associated with F3 use.
Castrating bombers by eliminating F3 would have a major adverse impact on game play. Isolating the A-20G for this treatment is solely based upon the fact that it is the best performing air to air bomber, and hence gets score of complaints from average (or lesser) players whose level of suckage is such that they can't cope with it in a fighter when the A-20 is flown my an expert. My advice is to improve your skills. Almost any fighter can beat the A-20 if the fighter's pilot has some basic ACM skills and adequate situational awareness.