Short answer: Zigbee devices and cloud integrations with SmartThings, local processing with Vera and better management of some advanced zwave features.*
Longer answer in the following thread:
*Advanced zwave features: scene controllers, association, secondary controllers, multi-endpoint devices. There’s usually a way to do something similar in SmartThings, and potentially with devices of multiple protocols, but since Vera isn’t afraid to go with zwave – only features, it typically has a smoother implementation of these.