If you are "into" history, CAO stands for Cano (pronounced john-no) A. Ozgener. He is/was a Columbia University educated Turkish mechanical engineer of Armenian ancestry. His family left the meerschaum pipe business to pursue what was at the time the more lucrative cigar industry where CAO became, and remains, a powerhouse. Ozgener began making meerschaum pipes because he was dissatisfied by poor way they smoked. (He owns over 2,000 pipes.) With his engineering background added to his passion, you can expect your pipe to smoke effortlessly.
CAO's carving wasn't always the greatest, but they used high-quality block, had a good draw, and smoked well. I think these are nice. Is the bottom one also CAO? I canalways spot that mustard-yellow case lining CAO used, but I can't see the lower pipe's case well enough to tell whether it's the same, or whether it has the more glossy tan-brown lining used by countless 90s-and-newer meerschaum companies (including CAO, after they switched from the yellow color).