App Store vs Appstore.
amazon is spelling it with no space between app and store as in appstore.
I have to say that with Apple's R&D budget being as miniscule as it is they really make too much fuss about their patents.
Businessmen and creatives must have at least a rudimentary knowledge of rules covering intellectual property. (Though registered at the PTO, this is a trademark, not patent, issue.) Anyone in these areas would realize why Apple must file suit.
Trademark laws govern confusingly similar terms. Clean Next tissues would infringe upon Kleenex. So the latter would appropriately file a cease-and-desist request followed by law suit if unresponsive.