As a professional Shoe Guy in outdoor retail, I must come to the defense of
variations in sizing/perception. To explain:

We carry one brand of footwear that builds their 'last' or foot-shape pattern
for each style/size to 'Brannock' (the sizing tool we use), or true measure.

If you measure to a size 10, your toes will probably touch the end of a size 10 shoe.

Another builds to 'proper' (my term) fit, meaning that their size 10 leaves room at the front.

In the first brand, you'll be more comfortable in a 10.5, in the second, a 10.
Once you know their design/intent, the variations make a bit more sense.
Since both are consistent in this, it makes things easier.

Clothing brands are most likely following the same model.

Now, to explain why I wear a 40 suitcoat and measure to 34" waist which translates
to a size SMALL in Columbia shirts and shorts? I have no idea.
And the guys who normally shop for XXL don't believe us when we hand them a Columbia XL.