Are there a lot of differences between the NUSSU Debit card and the normal DBS Visa debit card?

Honestly, I wouldn't say there is a lot of difference between the 2 cards because they both give 3% cashback on contactless spending. However, the NUSSU card is a mastercard and the other is Visa (not a lot of difference in that). The DBS Visa debit card is more convenient to be used overseas as it works in 11 foreign currencies.

If you are already holding onto the DBS Visa debit card, I would think there is no need to change to the NUSSU one because there is no particular outstanding feature of it.