Products vs Items
At first, the difference between an item and a product can be confusing. Let's start the explanation by discussing what an item is.
Items are ...
An Item is something you specify for a project. The screenshot below shows an item in a project. The name for the item below is "Chandelier" and it has been assigned Item Number 3. This item is going in the living room and there will be a quantity of 2 of them.
All of these details are Item Details because they are associated with this project-specific item and have nothing to do with the product which is a chandelier.
All pricing is item-specific. If you look at the Product Details below, you will see that this chandelier normally costs $1,015.00. However, if you look at the Item Details pricing section, the cost has been set to $999.00 This could be because the design firm was given a special one-time price, or because the chair is currently on sale. However, since the chair normally costs $1,015.00 the designer will leave the product price as is and change the costs in the pricing tab.
So the Item Name, Item number, quantity, pricing, and ship-to address are all Item details. If you used this product again for another item, all of these Item Details could be different.
Products are ...
Now let's look at the product. In the screenshot below, the red boxes indicate all of the product details. These details are specific to this specific chair and won't change if the product is used for other items.
Most of the product details are the attributes that you would find on the product's cut sheet from the vendor or manufacturer.
All of this information, the product details, and its images are stored in the Product Library. You can use this product in various projects and all product details will be the same.
The images are also part of the product. The same goes for Attachments in that they are part of the product.
All Items are linked to a Product
It is important to keep in mind that each item is linked to a single product!