It hires cheap people...
Home depot hires many people who are either contractors who work partime at HD, or part time contractors who works full time at HD. In either case they are knowledgeable in the stuffs in their department, and you can ask questions and get answers...
Lowes are supposed to be targeting a more upper-middle-class clientel, and it hires people from better family backgrounds but who are not handy. You can't ask someone who basically is trained as a cashier to tell you anything about what you need for fix houses.