There are three different cards... there is a basic Nordstrom retail credit card, that you can only use at Nordstrom stores (and Nordstrom Rack, the cafe, e-bar, etc). The other credit card option is the Nordstrom Visa -- this card you can use anywhere Visa is accepted. The advantage here is that you earn your Nordstrom Notes more quickly because you're using the card more often.
Note: Most people are only approved for the regular Retail card. If you have really good credit/earn a specific amount, you may have the option to choose which card you want. Not everyone gets the option. It's all credit based.
The other option (this is what I use) is the Nordstrom Debit Card (formally known as the Mod Card). This is a basic debit card which is linked to your checking account. You get ALL the benefits of the credit card, without going into debt. It simply deducts money from your account. You still earn points, which in turn become Nordstrom Notes (free money to use at the store). With all of the cards you're earning Nordstrom Notes.
On regular shopping days, you earn 2 points per dollar (for every $1000 you spend you get $20 back in Nordstrom Notes). During sales and other special times during the year, we have double point and triple point events. Next week, during the first 3 days of the Half Yearly Sale, it is double points. During Anniversary sale, the first 3 days are Triple Points. So... when you shop during these special points days, you are earning Nordstrom Notes more quickly. It's great! Free money! I use my Nordstrom Notes to buy lunch for the week at the Cafe.
There are also other perks as you spend more money (and go up the Levels)... which your sales associate can get into because I don't feel like typing anymore. Just an idea: free alterations, free shipping, etc.