Both tours are hiking on the ice of the same glacier. The difference are:
The minitrekking is:
Shorter walk (2 hours)
Less physically demanding.
It can be done by anyone between 10 and 65 years old.
Big ice:
Lasts 4 hours
You need a physical condition according to the duration of it.
The regulated age for taking up the activity is between 18 and 50 years.