Here are the major changes:
The source of funding
On prepaid accounts the source of funding is the card itself (= the card is loaded), on debit accounts the source of funding is the company's "available" amount (= the card isn't loaded, the account is).
On prepaid accounts, amounts are loaded on the cards. On debit accounts, what you see as the card's available funds is a limit set on the card, and if your "available" amount in the wallet is not above your card's limit, there is a risk that a payment might fail. This new behavior allows you to avoid blocking funds on your account if you don't need them immediately.
Example:
Prepaid account:
My subscription card shows 70 euros available, and my company's "available" amount shows 0. I'd like to make a purchase for the office.
Since my card is loaded with 70, I can proceed to my purchase. My Account owner can top up the wallet for other users / purchases later.
Debit account:
My subscription card shows 70 euros available, and my company's "available" amount shows 0. I'd like to make a purchase for the office.
Since my cards' funding source is not actually my card but the "available" amont of the wallet, I cannot proceed to my purchase. My Account owner should top up the wallet to have available amounts visible.
Budget / Available display on prepaid and debit
Although both debit and prepaid subscriptions/physical cards might appear as loaded, fully or partially, the funds are only "truly" loaded on prepaid cards. On debit cards, payments will go through only if the purchase's budget is lower than the "available" amount of the company wallet.