BlackBerry's emulation engine, rather than a platform-native app.
Dalvik in anything is theoretically the same as Dalvik on Android. Dalvik on BB10 is no more an emulation than Dalvik on Android. BB's implementation is getting better all the time, and reportedly will be Jelly Bean compatible in a short while.
Having said that, those Android apps on BlackBerry do show up how unsatisfactory a UI Android is. Use BB10 for a short period of time and you soon realize how stupid it is to have a home button in a fixed position on the mobile, and how crazy it is to have buttons at all. Native BB apps that use BB's bezel gestures are far nicer to use. It's a shame that app developers are taking advantage of BB' Dalvik to port apps in a lazy way rather than doing the job properly. However, BB would probably have very few apps indeed without their Dalvik implementation; beggars can't be choosers.