If you use a creator code you get a discount and the creator gets a percentage of your subscription fee.
If you *don't* use a creator code then you pay more, and the extra goes to the general Nebula creator pool (paid out loosely based on watch time).
You should generally use a creator code to sign up. You save money and the creator gets a piece of it. Unless you can't decide which creator you like the most and you'd rather pay more to have it distributed more broadly.