To me, the n90 swings heavier than the K90. It always took a lot of effort for me to swing the n90 consistently over a long period of time, but less so with the K90. The n90 feels like it has more weight in the throat area. Whether or not they really have the same balance I'm not sure and it's not even that important since two racquets with the same balance and weight can still have very different swingweights and dynamic feel on the swing due to differences in the weight distribution, and the n90 and the K90 definitely have different weight distributions.
BTW, all specs printed on the frame are for unstrung, while all specs on TW's product pages are for strung. 12 pts. HL unstrung = 9 pts. HL strung.