In order to differentiate trading companies from factories, you can ask them questions or analyze certain data that you already have available. You can ask trick questions like asking if they are a trading company, and honest ones will affirm it and if not, to be more sure they have told the truth and that they are really factories you can ask more specific questions like for example you could ask if you can visit the factory, if they are willing to have a third party inspection company verified and if you get a vague or negative response, they are trading companies and not factories as they claimed or you can simply ask for an explanation of a technical or material process and if it is a trading company, it will not know how to answer correctly, instead a factory will tell you all the details precisely. Other ways to make the distinction are to look at addresses knowing that factories are located outside a city or country, while trading companies are located in offices in the city. And you can also look at their range of products and if they have few types of products they are factories because they prefer to focus on producing only one type of product to do it best, instead, if they have a wide choice, they are trading companies.