Hi, Ray, while the components are similar, and some are interchangeable, the quality of workmanship and sound are far superior in the CX 12. I found I had to work harder to get a decent sound out of the Chinese knockoff. The CX 12, by comparison, is one of the easiest blowing harmonicas I own, including other Hohners and a Suzuki and Hering.
One thing John didn't mention: If you have problems with the CX 12, it's under warranty. The same can't be said of the WH 12.
The WH 12 was a good introduction, and an inspiration for getting a CX 12. I sold the WH 12 to a friend (who promptly dropped it and broke it beyond repair), and bought, over time, seven CX 12s, sold one to my friend and swapped one away. The remaining five get used, the white one the least because of its historical value.
Having started this Topic, I can welcome you, but you'll only understand why we like the CX 12 so much once you play one.
Or not. It has its detractors. It's just that the CX 12 is unique among the major manufacturers, and offers features no other harmonica has (WH 12 notwithstanding). And the biggest—literally—is the sound, followed by ease of playing.
All, as usual, IMHO.
Tom