No problem. A two-sided marketplace company is one like Uber, who recruits both drivers and riders to their platform, or Etsy, who recruits both sellers and buyers to transact on their platform. An example of a direct market is Apple, who sells their own product directly to the customer.
The main difference in terms of “groups” is that in a direct market, the company itself performs the service or makes the product. In a two-sided marketplace, the company recruits third parties to perform the service or make the products sold on the company’s platform. In almost all cases, these providers aren’t employees of the company.