Of course the extra expense is also because of the trouble they take in re-mastering the movies and all of the extras that they produce. Well worth the money though!
Not that it particularly makes much difference, but the amaray for Criterions is a different case to the regular US Blu-Ray one - it's clear and has no banner, and the spine is wider. I can always tell one of my Criterions from other Blu-Rays, simply because the full front face is taken up by the artwork
Of course, the titles released as digipacks are different again!