Custom properties and product compare

- Go to "Custom Product Properties" and enable "Activate Custom Properties" and "Activate Product Comparison"
- Click on the "Manage Product Property Categories" and create a category for your custom product properties, e.g.: "Notebooks"
- Add new "Custom Product Property Fields" to the previously created categoriy, e.g.: Size, Weight, Memory, etc.

You should now be able to select that propery category ("Notebooks") in the product's properties, when you edit or create a product. As soon as you select that property category, the additional fields will show up while you enter your product information. These fields are then used for comparing key fields between products with the same property category at the storefront.