Downloadable software where the main source of app discovery is Google rather than the App Store? (i.e. for Macs or PCs or both)
App Store: 600,000 competitors, success by any of which decreases your visibility.
Whole wide Internet: lots of other people writing software, but if they're not in your niche they might as well not exist. I don't lose sales just because DeliciousMonster launched.
App Store: sales curve starts with initial spike, then dies within 2 weeks.
Whole wide Internet: sales curve typically gradually increases as you tune your site and marketing with step increases at new releases
App Store: iFart
Whole wide Internet: you make apps people use on a daily basis for things that are important to them. They send you letters about how happy your app made them.
App Store: $4.99 is expensive
Whole wide Internet: $19.99 is cheap