e Pack
Case Pack
The Case Pack field allows you to define the number of items per case.
The general usage for this feature would be like this:
e.g.: You have a product that you sell for $1. If you set the items per case to 5, then the product can only be purchased in packs of 5, for a total of $5. The customer will see that your product costs $5, and that there are 5 products in the package. They will not see that the products cost $1 each (although they could calculate it manually)

The unit price is thus $5, which is NOT identical to your product price (since that value is $1.)

Inter Pack
The Inter Pack  field allows you to define the number of items per Inter Pack.
The general usage for this feature would be like this:
e.g.: You have a product which sells for $1 per package. If you set the items per inter pack to 100, your customer will see that this product costs $1, and contains 100 items.

The unit price is thus $1, which is identical to your product price.