the supplementary card is a derivative of the main card, which uses the funds and credit line of the main card, and the overdraft consumption is finally repaid by the applicant of the main card. The premise of the existence of the supplementary card is the existence of the main card, and its repayment and credit records are recorded on the head of the main card holder. Users of the main card and the supplementary card need to communicate frequently to avoid over-loading. In terms of points, it is best to accumulate the credit points of supplementary cards on the credit points of main cards.
the master card is the holder of the master card, and the master card holder has complete control over his credit card account and can use it as he wishes. The annual fee of the main card is generally higher than that of the supplementary card.
To sum up, the main difference between Metro supplementary card and main card lies in the relationship and function of the card. The supplementary card is a derivative of the main card, which uses the capital and credit line of the main card, while the main card is the holder of the main card, which has complete control over its credit card account and can be used according to its own wishes.