In Canada, we do not carry any Neutrogena makeup, only skincare, so I made sure that I picked up the Neutrogena Healthy Skin Makeup while I was in the states recently. I am jealous of americans having access to all this Neutrogena stuff, their products are really nice. It was $11.99 at Ulta (versus $40 for the NARS).
Neutrogena Healthy Skin Makeup in Classic Ivory (left), NARS Sheer Glow in Gobi (on right)
Colour match: I picked up the lightest colour they had, 10 Classic Ivory (I wear Gobi in the NARS). It matches pretty well, but it is more pink/neutral than the NARS, which is yellowish. I have a hard time finding drugstore foundations that match my skin, the colour selection of this foundation is small and it may be hard to find your colour, especially if you have dark skin.
Coverage: The NARS gives more coverage, and for me that is the biggest thing, but the Neutrogena provides good coverage too. Both make you feel like you aren't wearing any makeup. If you build up the Neutrogena, you can achieve a similar effect.
Application: Both blend nicely. I have dry-ish skin and both apply fine on me and look great. I use bronzer on top of this, I don't feel like I need to set it necessarily, but I prefer to.
Appearance: The Neutrogena can look ashy on me overtime, the NARS gives a smoother appearance and stays better, without moving or separating throughout the day, but it can start looking yellow on me over time, this isn't something others will notice however. I've heard that the Neutrogena does not photograph as nicely as the NARS, I tried it and yes, you get that white cast!
SPF: Neutrogena Yes (SPF 20), Nars No.
Packaging: It sucks on both foundations, they have no pumps and just a pour top.