They made some design changes and streamlined some things from a manufacturing perspective. Things I think they updated: Pulley system(no set screws), nozzle, extrusion carriage assembly(serious downgrade, you have to disassemble the whole thing just to adjust the nozzle height), comes with the 7.7 installed(IIRC, this may have been standard in 2014 as well), wingnuts instead of bolts under the bed are standard(a nice touch)...

I don't really know the 2014 model; those are just some of the main differences I've experienced from people with older models as I've had to troubleshoot and tinker.