Baritone Dulcimer?

Hi. In looking at dulcimer sites, and trying to choose a good instrument I have seen several that make Baritone dulcimers...confused now! Can someone explain the difference to me? What would be the reason to get a baritone as compared to a "regular"??? dulcimer?

Also, I have questions about chromatic or diatonic. I don't want to confuse myself any more than I already am, but want to understand the options regarding this particular instrument better, and the choices that should be considered when getting a new instrument.. Is a chromatic easier or better to learn, or a diatonic? These may be silly questions, but I really want to know why you would choose a baritone dulcimer, or a chromatic dulcimer....is there a particular reason you would want to learn to play a diatonic versus a chromatic instrument? Yikes! Any input will be greatly appreciated..Vivian