Apple:	Nintendo:
Market Share:	About 3-4% of the PC market[1], but a whopping ~77.9% of the portable music player market[2]	Third with about 17.9% of the U.S. game console market[3], but a combined 64.5% of the portable game player market[4]
Product lineup:	Has a smaller variety of software than its Windows competitors; much of this software is developed in-house, by Apple itself.[5]	Relies much more heavily on games developed in-house, particularly the Mario and Zelda franchises.[6], [7]
Advertising:	Heavy advertising campaign focuses on differentiating itself from the competition, to appear like the more appealing option to the general public. [8]	Well known for a strategy of reaching out to the so-called casual gamer, typically de-emphasizing the traditional market. [9]
Publicity:	Still positive, for now. [9]	As of now, still looking up. [10], [11]
Products:	White as you could possibly imagine.

Also of note: Nintendo Insider [1], [2]; Fanboy Intervention – this article is great [1]