Those lines don't matter to someone with very little or no experience. Go watch dogs of all sorts, and don't concentrate so much on the "big" lines but more on the lines of the actual dogs (so the grandparents, great grandparents, ect). It's not very difficult to tell the physical differences when you start hanging out with a lot of GSDs and really looking at their features.
But back to the temperament discussion...you won't know the difference. It's pretty much the same difference as one dog to the next...just a different personality. Yes...there are some patterns that have formed for each of the groups you mentioned...but its really not as big of a difference as people make it out to be. To an uneducated/unexperienced owner (like myself and many others) there pretty much won't be a difference.
Go watch dogs at the venue you wish to pursue. If its Schutzhund you're looking to get into...go the the club you're looking to get into. There is a very high likelihood that there are all sorts of dogs and breeders at a given club. You can see the males and females you like, find out where those dogs came from, and see if there are any planned breedings in the near future.
I would pretty much chalk up any difference you see from people's explanations to the fact that at the end of the day they are all different. They have their own personalities any many times people don't own dogs from the same breeding or a repeat breeding. Different parents = different dog.
CD RE TC HIC 7/10