Joined: Jan 2008
Posts: 23,643
Likes: 1,107
From: Mans of NC & SW UT Desert
Bikes: 86 Katakura Silk, 87 Prologue X2, 88 Cimarron LE, 1975 Sekai 4000 Professional, 73 Paramount, plus more
Go back to the shop, and find someone else to explain it. If you think it is confusing in person, over the internet will be more confusing. You bought the bike from them, they owe you clarity on how it works.
If you want to start learning basic bike nomenclature, spend some time on the Sheldon Brown and Park Tool sites.