Ajay said that funding ‘uncertainty’ (e.g., a new concept where there is no precedent set if the product work, sell, etc.) is when equity is used, whereas debt should only be used to fund known things (e.g., if you have inventory sitting in a warehouse and know that in the worst circumstances, you can still sell it).
For the latter, you can simply go to a lender and have them lend you $15k if you know, for example, that your inventory is worth 50 cents on the dollar. Lending and debt can help give you working capital, where equity is for the unknown.