MS gained critical mass as the PC market boomed - that's the only reason they are around. Until a few years ago they were also able to help hardware vendors sell new stuff by deliberately turning each new OS into a performance hog, helping vendors justify selling new stuff. Vendors in turn helping MS push their new OS because of reasons.
That aside, MS is mostly known for stifling innovation rather than bringing it on. The odd kinect or something aside.
Apple on the other hand always did well when the control-freak Steve Jobs was in charge. Say what you want, but the man knew what he was doing. His analysis of the market and his reflection on end-user computing in general were and still are fun and enlighting to listen to. Apple never, or very rarely, wastes your time with broad-strokes and/or half-assed bullshit. When they make a statement on their position or product line and why they have it that way it's usually spot on. With Gates and Balmer it is either boring or bullshit.
Steve Jobs was personally interested in building computers that don't suck. He truly wanted devices that he would use every day. His tantrums when someone delivered crap were feared and his persistance in pushing his people to better output was legendary. MS compared to Apple is like American cars compared to German cars. The German cars where all driven by the CEOs of the companies that built them themselves - in motor city each boss had a chauffeur. Ferdinand Porsche would notice instantly if a product he had was shit - because he used them every day. Crysler? Not so much. Look at Detroit today, and you know where that attitude lead them.
As much as I dislike a company having so much power, Apple deserves to be on top. They've turned tech-stuff into fashion and can ask 800$ for a new iPad from the next guy (and girl!) on the street. I won't fall for it - my Lenovo Yoga 2 is way better in every aspect and cost less than half - but most people will.
How MS can even remain in the market that strong is beyond me. Subscriptions for an Office Package? An OS? You've got to be kidding me!