"Connected" means that the FP is tied into the rest of that park's FP system. All of the attractions (including the Frozen Sing-Along) in DCA are "connected" to each other meaning that once you get a FP you have to wait until the time window opens up or two hours past, whichever comes sooner, before you get your next FPs. So, for example, let's say you pull an RSR FP at 9:00 am with a return time of 1:00 pm. You cannot get another "connected" DCA FP until 11:00 am (two hours after you pulled the RSR FP).
"Disconnected" means that the FP is not tied to ther est of that park's FP system. So you can get one and it does not impact your ability to get any other FP in that park. There are two DCA character meet & greets that use the FP/Return Ticket system (A&E and Olaf), along with WoC (the nighttime show).
So in theory, there could be a period when you have four FPs (A&E, Olaf, WoC, and an attraction).