Inventory Products allow you to assign a unique ccode to the product, as well as individual stock control. Whereas, when using Product Features, the number of products stock is global across all the different types of products.
However, Product Features are useful if the same type of features are used across various products. For example, if you are selling different t-shirts, but they all have the same variances of colours available, it will be easier to use product features as opposed to inventory products, where you will have to create separate product entries.