At its base level, 5G data refers to any data accessed via the fifth generation of mobile technology. The data itself may be exactly the same as 4G data, but the way it is accessed — and more importantly, the speed with which it’s accessed — may differ.
When a new generation of mobile technology becomes available, it’s not necessarily accessible at all times on all devices. With 4G, for example, many users deal with data caps on data accessed at 4G speeds. Unfortunately, data caps are also likely for 5G cellular networks — at least to begin.
For more info: 5G engineering