price & lot of things depend on the item doc but schedule
line  only concern about due delivery date & delivereble
quantity.

ITEM:-In this the system shows all the details of the 
item,like material,pricing,or it may be free good,ship-to-
party,batch,etc.
SCHEDULE LINE:-It is about delivery date and delivery 
quantity.

ITEM it should be control at item level in sales document
processing 

Sceduline control at sceduline level it should be relevant
to different delivery dates and different quantities takes place

in item category price is detrmined for the matrial and 
sceduline confirms the date for picking the material through
item category relevance

Item level: It controls the line item 

Pricing 
item relavant for delivery
credit active 
text item
Scheduline line allowed
weight volume relavant
etc


Schedule line:

It contain delivery date and quantity what the customer 
deliver,s