Product categories: Food vs. Food products vs. Animal vs. Vegetable

[Ludwig Paul Cabling]

Hello, I was wondering if there is any documentation differentiating the different product categories when looking at a a country's food import. 

For example, I am looking at Singapore's food imports by Products with the category of Food. How does this differ from the category of Food products? 

And is the Animal and Vegetable categories include products that are for food consumption? 

If someone can let me know where I can find some clarifying details on what defines these categories, it would be great - or if someone knows who to contact regarding this matter!

Thank you,
Paul