Prefinished doesn't have the same standards of grading as unfinished, nor the same terms.
The prefinished manufactures can call it what ever they want, whatever term they think will make you feel better about their product.
They can take the ugliest oak boards (definatley common grade) and mist stain on it until it looks good.
I would say Refiened would be the closest to select.
Here's a picture of a prefinished floor (was most likely graded something like premium)
https://lh6.googleusercontent.com/-zxOn ... 2%2529.jpgand here it is sanded and stained neutral
https://lh4.googleusercontent.com/-o3em ... 281%29.jpgQuite a difference on how the quality looks when the floors get sanded and stained onsite (and every prefinished floor will have to be sanded sometime) usually much sooner than the 25,50,100 year warranty's are up