Most of the popular applications have a set of servers that the application communicates with. The mobile networks can see the address of the destination of each data packet and match that with the list of servers used by an application and therefore find out which application you are using. It is similar to how they can have different charges for calling different phone numbers. The reason they can offer cheaper mobile data for certain applications is that they usually offer to host some of the servers in their own network. This means that the data packets do not leave the operators network and they do not have to pay any fees for uplink.
Latest Answers