Do developer NOC fees differ, and how much are they?

Yes. When reselling, the developer issues a No Objection Certificate (NOC), typically AED 500-5,250 plus VAT — reported examples include around AED 500 (Nakheel), roughly AED 1,000 (Danube, Emaar standard) and up to about AED 5,000 (DAMAC). Off-plan transfers use Oqood registration and generally don't need an NOC. Sellers usually pay it.