The two companies were actually a lot closer than people think, not the total strangers that most people would expect competitors to be.
In short, Apple and Microsoft needed each other.
Apple recruited Microsoft to be their first 3rd party developer, but wrote a clause into the contract stating that Microsoft couldn’t ship any software that used a mouse until a year after Apple’s first release.
In 1983, Microsoft announced the impending release of their mouse-based system, Windows.
Upon hearing this, Steve Jobs was far from happy. He accused Bill Gates of stealing from Apple. Gates responded, rather infamously, that is was more a case of them both stealing from a neighbor called Xerox, and Steve had just managed to get there first.
Gates was alluding to the fact that Xerox had actually been the front runners in some systems that Apple and Microsoft implemented in their respective creations.
Apple and Microsoft were always destined to be enemies, and a couple of years later Apple took Microsoft to court over a release of Windows that they deemed to be theft, however, Microsoft won a court case on a technicality and the two companies continue to be powerhouses in the computing world, but I doubt they have kissed and made up.
