Hi Heather! I always enjoy hearing from my fellow North Carolina residents here at the Moms Panel! To visit multiple parks on the same day, you must have the Park Hopper option on your tickets. You can't use a multi-day base ticket to visit different Disney parks on the same day. Without the Park Hopper, if you attempted to use your base ticket at a second park on the same day, the system would reject it, rather than taking an additional day off. Your base ticket will allow you to go in and out of the same park each day, but it won't allow you to visit multiple parks.
Although I can be frugal, I always pay the extra money to have the Park Hopper option on my tickets. I like to avoid long lines at the attractions, and when the park I'm visiting becomes crowded, I like being able to hop to a park with lower attendance. I don't always need to do that, but having the Park Hopper prevents me from getting stuck in an overly-crowded park. To me, that flexibility and the ability to avoid lines is priceless.
Have a wonderful vacation! Come visit us again at the Moms Panel if you have more questions! We're happy to help!