Hello, There is a lot of pilot being confused about the difference between: Altitude vs height vs AGL vs MSL ... It's very important to use the RIGHT words when talking about that subject and there is so many mistake around the different forums...
So, it's time to be careful and to call a "Cat" a "Cat" ... for the safety of everyone and to try to be a better pilot ...
My english can be incorrect as I'm from Belgium and speaking french (please do not confuse Belgium vs France ;-) so I will not try to make a long explanation but instead you will find hereafter a link giving you the right definition;
www.dronepilotgroundschool.com
And if you want to be "open minded" play the game and make the calculation of those "measure" in... meters ! Ok, ok,ok; it's a joke !
Bob
So, it's time to be careful and to call a "Cat" a "Cat" ... for the safety of everyone and to try to be a better pilot ...
My english can be incorrect as I'm from Belgium and speaking french (please do not confuse Belgium vs France ;-) so I will not try to make a long explanation but instead you will find hereafter a link giving you the right definition;

What is the difference between AGL and MSL? - Drone Pilot Ground School
In this article 1. Above Ground Level (AGL): Your Height Above the Ground 2. Mean Sea Level (MSL): Your Height Above Sea Level 3. So, What’s the Difference? 4. Quick Tip for Sectional Charts 5. What About Airspace Altitudes? Let’s imagine you’re flying a drone—or piloting a plane—and you want to...

Bob