WHAT DOES AJM SLOT MEAN?

I've an M1 Max Studio and an M2 Pro Mini.  There isn't going to appear to be any reason for me to update possibly.  I actually like & use all of the ports about the Studio.  Frankly I like the older Mini as well as the Studio sort things as well.  Apple will get carried absent with earning things thinner and smaller sized with out regard to uti