Wireless (or wi-fi) hotspots are essentially wireless access points providing network and/or Internet access to mobile devices like your laptop or smartphone, typically in public locations.
Typically wi-fi hotspot venues include cafes, libraries, airports, and hotels. Though many are free.
Wi-Fi Direct is used to connect to wi-fi, in the literal sense. Like you turn on the wi-fi and then the search for the available networks begins. You can select the desirable network from the list. In other words, we access net on our devices by connecting to others on a network.
Wi-Fi Hoptspot is a recent technology provided by Android phones. You can share your internet, whether packet data/3G with other computers. So here lies the main difference. But you won't be able to use the shared wi-fi in your phone simultaneously. In simple words, using this feature we share our phone's internet connection with other computers etc.