> What's the difference between a hammer dulcimer and a cymbalom?

The short answer is simply Eastern European vs. American names;
they're all similar instruments.  All can use all kinds of hammers,
woods, felts, and even bones.

There are many spellings, phonic and cultural, for many terribly
similar instruments.  Basically the cymbally, etc., are Eastern
European, notably to me, the Hungarian.  I have seen one that had
steel bands instead of strings.  I love the sound, and it got me
into balalaika music.

Try Wikipedia: musical instruments.  I enjoyed an evening there with
MP3s and demos.

Will Herzog