Discrete data is data that can be usual measured as a whole integer, continuous data doesn't usually include or round up to whole integers. That's how I distinguish between the two.
E.g. discrete data maybe number of students in a room, which maybe 20, but it is not possible to have 20.5 students, right?
Continuous data maybe temperature, 12.3*C where the temperature doesn't follow a set pattern, going up or down at anytime, during the day.
Definition I found online:
Discrete data is the type of data that has clear spaces between values. Continuous data is data that falls in a constant sequence.
Hope this helps!