There is no difference. Medium-sized restaurants are the result of the segmentation of catering services. In the past, catering services included all, but now that catering services are segmented, medium-sized restaurants are just one of them, so there is no difference.

A business license is a certificate issued by the industrial and commercial administration authority to industrial and commercial enterprises and individual traders allowing them to engage in certain production and business activities. Its format is uniformly stipulated by the State Administration for Industry and Commerce.

The registration matters are: name, address, person in charge, amount of funds, economic composition, business scope, business method, number of employees, business period, etc. The business license is divided into original and duplicate, both of which have the same legal effect.

The original copy shall be placed in a conspicuous place at the company's residence or business premises, and the business license shall not be forged, altered, rented, lent or transferred.

Industrial and commercial enterprises or self-employed individuals without a business license are not allowed to open their business. They are not allowed to engrave official seals, sign contracts, register trademarks, or publish advertisements. They are not allowed to open bank accounts.

Reference: Baidu Encyclopedia - Business License