I lived in Cary for a long time and also attended NCSU for grad school. I've been following the conversation on related sub-reddits and it seems like the biggest concern is what students are doing when they're not on campus: parties, crowded gatherings down Hillsborough St, etc. Community spread will still happen ... just that campus activities will not be the main driver.

The difference is the state government. Stanford doesn't exactly oppose the state's guidance, but I think their announcement makes it clear that they would have opened the campus if the state guidance had been a bit less strict.