Firms that export goods have lower profits compared to firms that sell only within their country. This is because exporters aim for higher revenue by reaching a larger market. Small and domestic firms tend to have higher mark-ups, which are the differences between production costs and selling prices. In sectors with many firms and low capital-labor ratios, mark-ups vary more. Service sectors generally have more diverse mark-ups than manufacturing sectors. Overall, different types of firms cater to specific market segments with varying demand.