You can offer one group some special discounts that you wouldn't want to give the other. My primary job at this website is to create some questions to make you think about the subjects I cover and consider all your options. Don't just read a book on any business subject and throw caution to the wind and put it into practice without careful thought and planning. You may get the impression from this article that I am not a fan of niche marketing. That's not true.
Niche marketing can and does work well in certain circumstances.
There are certainly enough books and articles written on the subject. Search this site by keyword.