At what age can you take diving courses?

The age to take “Diving experiences" is from 10 years old, while for “Diving courses" is from 18 years of age.

The certifications will come with the legend of the course taken with the completion Jr. For example: OPEN WATER DIVER Jr. When they turn 10 years old, they become Senior.

What's the difference between one and other? The difference will be in the maximum depth to which they can go down.