Question about Amazon Purchase?

Neither.
Amazon collects the money from you.
Once you have paid, Amazon notifies the seller to ship.
You receive. Amazon pays the seller once a month.

This works for both buyer and seller. Buyer can use whatever payment they have on file with Amazon. Seller does not need the infrastructure/bureauracy of wide range of payment methods. Amazon makes money in the transfer and also sets reasonable shipping cost (unlike eBay where cost could be small but shipping is large).

Since Amazon keeps the money "in escrow", you have the option to dispute if there is a problem.

If the item is being bought NOW (as in, the item is already released), then you get charged as soon as you hit checkout.

If the item is a PREORDER, then you get charged once it ships.

You pay through Amazon first, like you normally would as if you're buying from Amazon. Then they give the shipping information and the money (minus fees) to the seller.

You will have to first pay for the item before they ship it. This prevents them from sending products to customers who will simply not pay.

Hello, after you provide your payment information and click "Place my Order", your source of payment will not be charged when your item ships. Therefore, Amazon charges the money first and then ships but not right after you placed your order. I hope this helps.