To my eyes, there is very little difference between them, you could always reduce the noise very slightly when making an enlargement, that is something I prefer to do. I'm sure there are not many image editor programs that would enlarge a picture with no loss of quality, especially with jpegs
The more I use and play around with Paint.NET, the more tempted I am to uninstal Photoshop CS5, The plugins available in PdN are not only far better and very well written, but the menu and layout is more user friendly. To make a simple adjustment in PS is always a case of "now where is that feature" But in PdN, there is the - Effects > Advanced > Script lab that I use for searching for an effect.