If you go to swappa.com/esn and enter your IMEI number, it'll let you know what model it is.
Me and my mom have T989s, but my dad has the I727. The I727 has a more rounded (smooth) feel to it. The T989 is more squarish at the edges.
Nook Color running CM7 Mirage, no gapps, Nook Tweaks app @ 1.3GHz (+500MHz past stock 0.8GHz)
Nook Tablet running CM10.1.3, no gapps, BexusNv4 kernel @ 1.3GHz (+300MHz x2 past stock 1GHz)
SGS2 T-Mobile (unlocked) running HellyBean 4.2.2, no gapps, @ 1.72GHz (+~200MHz x2 past stock 1.51GHz)