So the first card allows you to hold the BTC in the account. When you make a purchase you get the spot price at the time. Yes there are fees etc, so you don’t get full value, but there are always fees somewhere.
The second card involves you selling the BTC when you load the card. In this case you have to be happy with the price at the time and not look to the future price of BTC. BTC might go up so you have missed out on some increase in value. BTC might go down so you loaded the card at the right time. The same with any asset that you convert to fiat (£GBP).