Note, this answer largely deals with the Americans. Of the major warring powers, the US had the most extensive and far-flung aerial operations. And for clarity's sake Pacific Theater (PTO) and European Theater (ETO) speaks for these theaters in the broadest sense, including areas like the Mediterranean (MTO) or China Burma India (CBI) that were nominally separate in this nomenclature.

The differences between the type of planes employed in the ETO and PTO was largely the intersection of immediate tactical needs, the prioritization of certain theaters over others, and institutional rivalries between the USN and the Army. This constellation of factors varied throughout the war, but it did result in certain types of planes dominating the picture of the American air effort in their theater.

The Army Air Forces in Southwest Pacific Theater in 1941-early 1944 exemplified this trend. In 1941/42, the SWPac's 5th Air Force did receive then front-line equipment like the P-40, P-39, and B-17s to stem the Japanese tide in New Guinea and the Solomons. But these aircraft tended to be adequate for the job, they were roughly on par with their Japanese equivalents. The emerging 8th Air Force campaign against German industry in late-1942 meant that the 5th Air Force received fewer B-17 spares and replacements. Moreover, the B-17 level bombing was inadequate for destroying Japanese shipping even though the bomber's performance envelope and robust construction made it difficult for Japanese planes to intercept. 5thAF commander George Kenney thus pushed for twin-engined bombers in the interdiction role such as the A-20 and B-25 and built upon skip bombing techniques developed by the RAAF. These medium bombers were in less demand for the ETO and their performance was ideal for the New Guinea theater. Medium bomber successes like the Battle of the Bismarck Sea and other strike successes, coupled with their often garish schemes such as those of the 499th Medium Bomber Squadron imparted to these medium bombers a wider public memory postwar. Many of the same medium bombers were used in the ETO, especially in the Mediterranean, but they did not have the same historical record or memorialization associated with them, Catch-22's B-25s excepted. Conversely, the 5th AF often had to make do with the older generation of fighters as the ETO sucked up a number of the more modern fighters. The 35th Fighter Group had to swap out its P-39s and P-38s for P-47s in late 1943, but would only receive P-51s in 1945. The P-38 was a major success in the SWPac, where its heavy armament and range were clear advantages, but proved to be a disappointment in the ETO where high-altitude operations played havoc with its engine fluids, and the high performance of the Luftwaffe fighters brought compressability problems to the fore as the ETO P-38s engaged in dogfights. Therefore, although the P-38s in the ETO had a decent record, they did not have the type of aces like Richard Bong or Thomas McGuire. The SWPac Mustangs and Thunderbolts also found while they outclassed their Japanese enemies, the attritional battles of 1942/43 and collapse of the Japanese logistical network meant there were far fewer targets as Japanese airbases were short of fuel, pilots, and planes.

In some cases, interservice rivalries played an outsized role in the absence of plane types in certain theaters. In theory, the F4U met a number of requirements for an AAF long-range fighter in 1943. But this was a Navy plane. There were long-standing prejudices within the Army against using an aircraft developed for use on aircraft carriers. This was not as myopic as it would appear at first sight. Carrier aircraft need specialized equipment such as strengthened landing gear, tailhooks, and like which added a significant weight penalty. Although the performance gap between carrier and land-based aircraft rapidly closed during the war, many of the officers in Army procurement had experience with the types of planes in the 1930s. The preconception was that a Navy aircraft could not meet the needs of the Army. But, in addition to the "not developed here" syndrome, both the Navy and the Marine Corps had earmarked the Corsair for their own uses, as well as the various Lend-Lease navies and air forces of the Allies. Sorting out the procurement priorities would have taken time, and updated P-47s and the new P-51s offered a more convenient plane of the ETO. Moreover, while it was possible to make the F4U into a land-based fighter, as the USMC did to great effect, making the P-51 or P-47 into a carrier fighter would have been quite difficult given their landing envelopes and lack of carrier equipment. Therefore, the only Corsairs and Hellcats used in the ETO in large numbers were the FAA's lend-lease, which were involved in strikes in Scandinavia and the invasion of Southern France.

Other aircraft became the unique preserve of one theater because their performance made them the only ones suitable for the job. The B-29 fit in this category. Existing B-17s and B-24s could hit most of the targets in the ETO by 1944, but the ranges to attack the Home Islands from bases in China and the Pacific needed the B-29. Assigning the B-29s to this area fit this need as well as providing a salve to the Army and Navy men in the Pacific who were stung by the "Europe First" priority of the Roosevelt administration.

Finally, as the examples of Catch-22 or various models of the 499th show, postwar culture played an important role in emphasizing some aircraft types over others. The B-17 had an advantage over the B-24 postwar as movies like Twelve O'Clock High, Command Decision, Memphis Belle, and Red Tails helped to make it the face of the 8th AF's bombing campaign. While the quality of this media was quite variable, it helped fix the image of the B-17's tall tails in public memory. The WWII documentaries produced postwar scrambled for newsreel footage and often elected for B-17s, especially since the Boeing plane's durability provided dramatic images of shot-up aircraft returning to base. In contrast, the B-24's most prominent brush with postwar memory was the discovery of the ill-fated Lady Be Good in Libya, which inspired the classic Twilight Zone episode "King Nine Will Not Return," albeit using a B-25. Although veterans of both planes wrote their tales and created their own reunion cultures, the B-17 fit more easily into existing public memory as the plane that fought over Europe (and it helped that B-17 veterans had a much fonder experience with the docile Boeing plane than the more difficult to fly B-24). This postwar memory-making process- replicated, repeated, and reified in a myriad different forms and media- helped some aircraft types become more prominent in the public's mind even if their less famous stablemates served with distinction as well.