How is the Price of crypto determined?

I get that supply and demand is the obvious factor and that I understand that the process is largely automated, but what factors within the code influence price changes on an exchange? For instance, why is Bitcoin be priced at $20,500 on Coinbase, but at $21,500 on Binance?

I'm just wanting to know about how pricing mechanisms function on both centralized exchanges and decentralized exchanges, as I assume they employ similar methods for determining price? Like is there something in the code that goes “ X amount is sold, X amount volume on exchange = X price?

I’ve never really thought about how prices are actually determined (code side of things) so any more knowledge or insight would be good to read!