The base-model iPad (starting at $329) has a 9.7-inch display with a 2048x1536 screen; the iPad mini 4 has a 2048x1536 screen as well, but it measures 7.9 inches diagonally, offering a compact display with better pixel density (326ppi versus 264ppi). read more
As I mentioned, the iPad Air has the same specs as the iPad mini 2 and the iPad mini 3; therefore if you choose the iPad mini, get the mini 2 rather than the mini 3. The only difference between the two is that the mini 3 has a gold color option and Touch ID, but it costs $100 more than the mini 2 for those two features alone. read more
Still, it's worth noting: The iPad mini possesses all of the iPad's capabilities. Owning an iPad mini means you're sacrificing screen size more than anything else. Overall Size. The iPad mini is definitely easier to carry around, putting the "mobile" in mobile device. read more