A Seller's permit is a license issued by the state to businesses allowing them to sell and collect sales tax from customers in their state. The seller is then responsible for submitting the collected sales tax to their state on a monthly/quarterly basis (depending on the terms of the state).
A resale certificate is a document you would issue to wholesalers/suppliers if you want to make tax-exempt purchases for products you wish to resell.
This certificate is proof that the wholesaler/supplier has sold you those products without tax charges. Instead, you'll be responsible for collecting the sales tax from customers and remitting it back to the state.
Difference between a Seller's Permit and a Resale Certificate
A seller's permit allows you to collect and remit sales tax, while a resale certificate will enable you to purchase items tax-free (for reselling).
While a Seller's Permit is necessary to do business in a given state legally, you only need a resale certificate if you want to make tax-exempt purchases from suppliers/wholesalers.
You need to apply for a Seller's permit from your state, while a resale certificate is something that you would give to suppliers/wholesalers that they can use as proof that they've sold the products to you tax-exempt.
For more information, you can check out our blog post on the topic — Seller's Permit & Resale Certificate: What's the Difference?