You may perhaps find the following entries from  The Fiddler's Companion helpful:

BARNDANCE.  A two-hand dance form in Ireland, thought to have been originally introduced from England, where they still exist.. Caoimhin Mac Aoidh says: "Barn dances and Germans - These are the same thing.  The term German seems to be restricted to west and central Donegal.  They are in 4/4 time and played at the speed of a hornpipe.  Their characteristic is in the rythym of the tune.  Typical barn dances have a recurring set of two or sometimes three crochets (quarter notes) at the end of a number bars which give it a very determined rythym.  Hornpipes can be easily pared down to make a german.  As for their geographic spread, see my comments above of highlands though barn dances are appearing to be on the increase outside Ulster."

GERMAN.  The generic name used in (northwest and central) County Donegal, Ireland, for a 4/4 time Barndance tune.  The tempo is close to hornpipe speed.  Caoimhin Mac Aoidh (1994) states the structural characteristic is groups of two or three crochets used to accent the dance.  The name German for this genre is thought to have dervived from titles on sheet music covers of about a century ago, which identified tunes as "German Schottisches" or "Highland Schottisches" as the case may be.  Mac Aoidh speculates that older musicians, lacking formal musical training, probably assumed that by implication the two were different.

HIGHLAND.  A dance form with accompanying music in 4/4 time.  The name highland is a regional name in northern Ireland for the dance form elsewhere usually called a schottische.  It is also called a German, and elsewhere in Ireland is called a fling, highland fling or highland schottische.  According to Caoimhin Mac Aoidh (1994) highlands were adapted by Donegal fiddlers from strathspeys and reels, and are played much slower than a reel but faster than a Scots strathspey.  When borrowed from a strathspey the triplets tend to be simplified.  In previous times the Highland/Fling/German form was to be heard played over much of Ireland, however, in the 20th century they were increasingly confined to the northern counties, principally in Donegal.


Malcolm