I guess the answer just isn't obvious to me. Why do these two different masses differ? Why do they report different weights? The report on the bottom right is stock, of course. The report up across the top of the screen (and the tiny one on the bottom left) are thanks to KER. KER is awesome and my favorite, and I am leaning towards trusting it's numbers over the stock game's numbers. I linked it for anyone that's new or never tried it before.
Does anyone know why this discrepancy exists, and which one is the accurate one? I have started a second save with a pretty drastically different mod set; it contains KSPI-E, along with a number of other really cool and complex parts mods, and with a bit more difficulty to it (I guess this isn't very relevant). As such, and because it's still pretty early in this career, it is really important for me to know which one of these is correct. Even if the stock one is wrong, it doesn't seem to matter because that's what the game goes off of for determining if the launch pad can support the rocket (I just started this new career, it's still a un-upgraded launchpad).
KER says the mass is 7,740kg's, and the stock game recognizes the ship as being OVER 9000!!!! (kg's)
http://imgur.com/ocsAAdS
As always, thanks KSP community