Hartmann was trained under German ace Walter Krupinski--in the tactic of the surprise attack. The strategy was "See, Decide, Attack, Break". The notion that he waited until the target filled his windscreen was only part of the equation, especially at first. Krupinski was known to constantly tell him to move in closer before firing. The combat doctrine I mentioned above was never to be broken--it was the standard rule that he used throughout his whole time in the cockpit. Of the two pilots, one would attack while the other stayed "on the perch", watching his back. Of Hartmann's 352 confirmed kills, 345 were against soviet opponents.
Marseille, on the other hand, flew exclusively against western opponents. He also had a reputation for being practically reckless, with his tendency to dive headlong into enemy groups and disregarding orders to keep formation. Early on, he was reprimanded and punished more than once for his failure to work as a team. He did perfect high-deflection shots, but at the same time this is again only part of the equation, as he always ordered his wingman to stay far off. He would then attack enemy groups alone, and since his wingman was far off, there was not much risk of the two of them colliding into each other. All but 7 of his 158 confirmed victories were British Desert Air force pilots.
The marksmanship was only half the story--Hartmann was very disciplined in his tactics as an unbreakable rule and relied heavily on his wingman. Marseille was a loner in the air and would charge in undaunted even when it was unwise to do so.