The difference between the prefix 5 and the prefix 6 of China Merchants Credit Card is as follows:

5 is a Mastercard card, which was founded in 1966 and has its global headquarters in New York, in the eastern United States. As the world's leading payments company, Mastercard is committed to providing global consumers with a more convenient and efficient financial payment environment.

6 is a UnionPay card. UnionPay is a joint-stock financial service institution approved by the People's Bank of China and jointly established by more than 80 domestic financial institutions, with a registered capital of 1.65 billion yuan. The company was established on March 26, 2002 and is headquartered in Shanghai.