Applying at Nordstrom
At Nordstrom you don't work for MAC, you work for Nordstrom. You may be considered a MAC employee through MAC, but at Nordstrom you are considered theirs. You only represent MAC in their eyes. Although you will probably be interviewed by someone from MAC along the way, the people who you will go through first are the people at Nordstrom. And if they don't like you... then you won't even get past them.
I would make it ultimately clear that you are passionate about cosmetics and that you care about Nordstrom, too. Don't let them have a reason to not hire you. Because saying that you only care about the vendor is a good reason for them to skip out on you.
I don't know how it has been with people sent from MAC to Nordstrom, but I know if you yourself are personally going to Nordstrom looking for a position with MAC, you are reviewed by them for a cosmetic position - no frills, and then how they feel about you determines where you will be placed in the department.
I went in there interviewing for MAC, and then was throw into Smashbox. Trust me, coming from someone who works for Nordstrom, make it clear that you care for Nordstrom as well. They're big on devotion.
Goodluck!