Continuity
Apple doesn't seem compelled to blur the lines between iOS 8 and OS X 10.10 as much as obliterate them, at least where it makes sense to. Continuity is what Apple's calling that — design that enables one device to complement the other. Handoff, for example, lets you start an activity on your iPad or iPhone and continue it on your Mac. And Instant Hotspot lets your Mac use your phone more easily. SMS and MMS messages sent to your phone will automatically appear in Messages on all your devices; you can even make and receive phone calls on your Mac when your iPhone is on the same network.