What is the difference between the loop liner and the hook liner inner belts?
Loop(soft side) and Hook(hard side) are like the two different sides of vel cro. So you need the opposite of your duty belt so the two stick together.

IOW: make sure the vel cro on the inside of your duty belt is reversed from the vel cro on the outside of your inner belt so they stick together.

The vel cro on the outside of this inner belt is loop(soft side), it can only be matched with the outer duty belt which has hook(hard side) liner on the inside.

Casual concealed carry belt or combined with outer belt.

Hikers should probably consider this for your pants, because you can still strap the heavy duty back pack belt over this without pain from a buckle.

It's also machinist friendly and these are perfect for not scratching anyone's car.