Good question! Well generally show Mals have a thicker, fluffier coat and have a thicker frame. This is typical of a Malinois from show lines:
http://www.kennels.co.uk/images/BSD.Malinois.jpg
I've most often seen working line Mals with sleeker coats and thinner, more agile looking bodies. But it does vary with working Mals too. I've seen some really solid built dogs from working lines. Temperament differences are night and day too. Keeva is half American show/half working line. She is drivey at agility and on sheep. But she has an off switch at home and is just like any other family pet. Kwik is 100% Czech working lines. She has no off switch and lives to work. Her drive is a challenge because she doesn't always hear me once she is working. I taught obedience classes for years and fostered for Border Collie rescue.. She is unlike any dog I've ever met :p
