KitKat versus Jelly Bean
KitKat looks like Jelly Bean, but under the hood it’s a whole lot better
Android 4.4 KitKat looks like Jelly Bean: What are the advantages of KitKat vs. Jelly Bean?
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What is TRIM support in Android 4.3 and why should you care?
The original Nexus 7 got slower with use. The problem was identified, Google pushed an update that enables Android TRIM support, & fixed the issue.
Here's How to Set Up and Use Multi-User on Android 4.2 Jelly Bean
Google explains lack of multi-user mode on Android phones
Find out what Google has to say about the lack of multi-user Android phones, despite tablet support.