Any autoharp fans/experts in the house?

[john-o]

My wife is a teacher, and was moved from middle school to preschool this year. She just recently mentioned that she might like an autoharp for Christmas, as music is so important in her classroom now. I found a site called instrumentalley.com, with a couple of decent deals, but I'm a bit over my head here... The two models are these:

Johnson FI-320 21-Chord Autoharp Chorded Zither; for $199 on sale and free shipping, and...

Oscar Schmidt OS21C 21-Chord Autoharp; for $230 plus shipping...

I wonder what "chorded zither" means, when appended to the name of an autoharp? I tried calling them, but got no answer.

Anyone have a clue?

Many TiA, as usual!
John