Variations are inventoried items that have unique product codes / SKUs. For example, a t-shirt may be sold in different sizes, like small, medium or large. These SKUs are related to each other through parent / child relationships. The main product (shoes) called the parent product and the variations (small, medium or large) are called children.
In the example below the parent SKU is 217 and the children are 217_1798, 217_1799 and 217_1800.
This will display as one product on the website front end with buying options available from a drop down menu.
Specifics are the properties of each product or SKU. These can be used to differentiate the variations or can be added to products to create filters (ways to narrow a search) on the website front end.
In the example below the variation (child) SKU 2968_chocnut has the specific Flavour with the value Chocolate and Nuts.
Specifics can be used to offer your customers ways to narrow their search and will be visible on the front end.
Extra options are non-inventoried extras you offer the customer at the point of purchase. For example, the option to pay for gift wrapping or enter a gift message.
Kits are ways to bundle items together to be sold as one unit, e.g. gift hampers.