How does an android differ from a bb? I mean what are the features?
technically? not much. They are very similar. The way they work and operate.
in the end users hand. VERY different. Basically an Android phone is a Linux Powered Micro Computer that can make and receive phone calls. Blackberries are just a middle of the road smartphone.
where do the vast changes come into play, being they are similar? two words " Open Source ".
Features?
Browser, Media, Applications out of the ying yang, E-Mail, Instant Sync with Google (Calendar, Browser, Contacts, E-Mail, Google Talk). COUNTLESS others... and if you get into Rooted Androids the benefits expound in an exponential curve.