Introduced in October 2021, Genie+ is the paid version of Genie, which is a feature on the My Disney Experience app that helps park ticket holders plan their days by suggesting rides and attractions to see based on interests and availability.
Genie is available for free to simply provide suggestions on how to structure your day around which rides you most want to go on or around specific themes, like princesses or thrill rides, view current ride wait times and closures, and see the schedule of shows, parades, and nighttime spectaculars. You can also make restaurant reservations, including for character dining, and order and prepay for meals at eateries that offer counter service.
By paying for Genie+, not only could I access all of the other Genie features, but I could also grab Lightning Lane access for certain rides. Lightning Lanes are the express lines that allow visitors to bypass the regular, often very long lines for rides, cutting their wait times sometimes by a lot. Lightning Lanes replaced FastPasses, which for years were Disney's free, popular "cut-the-line" option.
Regular Genie users can access Lightning Lanes, but they have to pay for each individual Lightning Lane reservation. Paying Genie+ users, on the other hand, get unlimited Lightning Lane access, albeit with many caveats.