Until very recently, I would have assumed the title of this post "Macaroon vs. Macaron" to be a typo. Some of you reading may actually feel the same way. These are actually two different pastries.
If you're like me, you're probably more familiar with the macaroon. The most common form that I see is the standard coconut macaroon -- a yummy mound of shredded coconut (hopefully moist), sometimes dipped in chocolate. Additional varieties include the almond macaroon -- similar to a meringue with almond paste. And even the amazing pistachio macaroons at Mike's Pastry in Boston.
Macarons, on the other hand, are an amazing creation consisting of flavored ganache sandwiched between two thin meringue-like cookies. I recently discovered these cookies at a yummy restaurant / bakery near my office called Sportello. They have flavors such as pistachio, hazelnut and chocolate. A quick Googling around the Web points to lots of different varieties -- particularly in their country of origin - France. If you like meringue's, you'll love macarons.
Macaroons on Wikipedia
Macarons on Wikipedia