Great question! For this pack, the only difference is that you'd download the asset pack from Patreon instead of from itch. For patrons, I give out itch keys manually for this pack on request since it works a little differently than other packs on itch's end. For almost all other packs, connecting your itch and Patreon accounts lets you download and claim the pack on itch. Becoming a patron also means you'll get access to new packs when I publish them. If you pledge on Patreon and then cancel later, you still get to use all the asset packs you've downloaded- You own them.
In the end, it's just two different ways to support and get the art, and it's your choice! Some folks like to support on Patreon and stay in the loop and help me make more art, while others prefer a one-time purchase or prefer not to set up an additional account. Let me know if you have any other questions about it!