Understanding different item types

Dear All,

Can u please suggest difference between following class of items & also their usage. Or please please suggest any documentation where I can find this information.

•      ATO Model

•      ATO Option Class

•      ATO Item

•      Finished Good

•      Kit

•      Outside Processing Item

•      PTO Model

•      PTO Option Class

•      Phantom Item

•      Planning Item

•      Purchased

•      Reference Item

•      Subassembly

•      Supply Item

•      Freight

•      Product Family

•      Equipment

Thanks in Advance!