Premium is different in both how it functions and how it's setup.
Premium, and the new donation bot, have been written from scratch for the sole purpose of being used on Darkly servers. This means it that, unlike Store, it is not reliant upon a third-party plugin development team; Darkly administration are the sole developers. Thus, making modifications, improvements, and fixes to the Premium system is considerably easier and faster than the Store system. If you have a bug to report or an idea for a feature, we'd love to hear it.
Premium is also entirely contained. Unlike Store, it's designed to house all Premium features and functions within one plugin, rather than rely upon other extra plugins or external databases. This dramatically improves stability/efficiency, and makes troubleshooting problems much easier. Premium relies little upon external databases; should a database go down, players will only not be able to donate for credits. All existing Premium players will still be able to fully use their abilities.
Premium is divided into packages. Players can exchange their credits from donating for any of the available packages. This means you cannot purchase individual perks, like in Store. Additionally, all Premium packages last 1 month rather than the previous 5 days. Any single-use items that are part of Premium instead are unlimited use and have a short cooldown between uses.