Adapter or Express Card ?

Whats the difference between a laptop adapter and a laptop express card ? I would be pairing a D-Link DIR-655-Xtreme N Gigabit Router with either a D-Link Xtreme N Laptop Adapter or a D-Link Xtreme N Laptop Express Card on a Macbook, but honestly I'm not sure if I need the adapter or the express card. Judging by their product descriptions, they seem like identical products. Which one do I need for my application ? Thanks in advance.

 

I don't know. Heck, I've don't recall that I've ever even heard of Express Card. Anyway, I thought I'd mention this website, in case it's helpful to you: http://www.expresscard.org/web/site/qa.jsp#01

I presume the D-Link Xtreme N Laptop Adapter is a USB device, and the D-Link Xtreme N Laptop Express Card is a PCMCIA card, right?