GrandNode supports different types of products within a single store.
A simple product is a physical item with a single SKU. It can be sold as a standalone product, or as a part of the bundle kit. Simple products are also used to handle associated products in the grouped products. A simple product can also represent the variants of the product, with attributes combinations it will show all possible variants like 42 sized red shoes. Read more about combinations in the product attributes section.
A grouped product represents a product that is available in variants - for example, we have a Football shirt - Home and Away. You are able to sell it as Grouped Product "Football Shirt" with associated, simple products "Home Shirt" and "Away Shirt" with independent attributes, SKU, price.
A bundle product is some kind of a grouped product. It contains a bunch of simple products but with an independent price. The best example is a PC Kit that contains a PC, Monitor, Keyboard, Mouse, and two games. Each product can be purchased independently, but you are able to sell it as a product kit/bundle pack, with a cheaper price.
Downloadable products are rather a feature than a product type because you are able to create them directly from a simple product, by changing the value of the Downloadable product setting to True.
If you use this product type, you will be able to create a product that will be able to order or bid. Each auction product has an independent counter. There is also a short guide about creating an auction product.
A reservation product type may be used to create products that are available to rent or book. There is great material about managing the reservation product type.
It's not a typical product type. You can create gift cards - physical or virtual - from the simple product. All you need to do is change the settings Is gift card value to True under the Additional Info tab during the product creation. Then you will see a new dropdown field Gift card type - you will be able to determine if it's a physical or virtual gift card. In both cases, a gift card will be applicable on the shopping cart step.