Hi! I read that there are (at least) two key systems for the clarinet: the Boehm (the one prevalent in US), and the Oehler.
What’s the difference, please? Is one more difficult than the other to play? Is there a difference w/r/t the note pitches?
Thank you. 
I found this: http://www.sneezy.org/Databases/Logs/2000/02/000521.txt
using http://www.google.com
Any help?
That really helped a lot!