No difference. Grand opening and grand opening have similar meanings. They both mean that the opening is very big, crowded and lively, so there is no difference between grand opening and grand opening. The opening ceremony refers to the relevant units in the business community celebrating the establishment of the company, the company's anniversary celebration, the start of the enterprise, the opening of the hotel, the opening of the store, the opening of the bank, the opening of large buildings, the opening of roads or waterways, trade fairs or A grand ceremonial procedure held for the opening of an exhibition, etc.