Xmas 2013 Takedown (speculations)

I need tech advice on something. Never used two separate devices before, but now I swap between my Nexus and our iPad. Can i update on my old faithful non-crashing-but-standard-resolution iPad, where I know how to get to the app update screen, and then when I turn on my often-crashing-but-beyond-awesome-Nexus, how do I avoid crashing my whole town when I go to my second device? Will the town exist in both modes until I update both, or???

(Picturing my older brother shaking his head hearing me ask this, and muttering "Sheesh. Girls.")