As part of the "S" Series, the NF-F2S is the oval hole version of their popular NF-F5S.
The main structural difference between the two mandolins is the F2S's oval sound hole. The F2S also has a darker stain on the back, sides, and neck.
Tonally, Northfield's oval hole and F-hole mandolins are in the same family, so if you like one you'll probably like the other. That said, we feel the oval hole models have a subtly warmer, fuller tone with a bit more low end.
While oval hole mandolins typically don't produce as much volume or "chop" as their F-hole counterparts, many solo players love them for their sweet, overtone-rich character.