Hi Peter...App. is "long stringy thingy"--traditionally single noted with drone strings, gives bagpipe effect, which helps to explain the popularity in the southern mountains where the Scots/Irish root music was strong. Hammered is a board zither struck with hammers, derived from the psaltery. Apps can be and are often chorded. This is easier with a small scale fretboard (length of instrument determines scale--ratio). I wouldn't suggest any multi-string things such as autoharps or hammered dulcimers for a beginner travelling-too many tuning problems. This link doesn't always work, but if not try Lark in the Morning and check the Mountain(Applachian) dulcimers....there is a small one listed with a sound clip for, I think, $65.00 US.

Spaw