Market orders are transactions meant to execute as quickly as possible at the present or market price.
Market orders are optimised for speed. You can buy gold(precious metals or cryptos) very quickly but you can not decide the price. The market determines the price, you can cease that by placing and order at a time there is a favorable price for you.
A market order is a request for gold or bitcoin at any price starting from the cheapest. It buys's or sell's everything instantly for any price that other people are selling or buying for.
This is the fastest way to buy or sell, especially when the market price is moving quickly. Be careful using this order type. You might buy or sell at a price you don't want to. Keep an eye on the order book to see the volume available for purchase or sale.
Limit orders set the maximum or minimum price at which you are willing to buy or sell.
A limit order allows you to fix the price you want to buy gold for, but you have no control over the speed at which the order will if filled, if it is filled.
This means if you set a price to buy gold, you will never buy gold at a price higher than you have set a limit for. If you sell gold, you will never sell gold below your set selling price limit.
The issue with a limit order is that if the market price is moving fast your orders can be left behind, meaning you could end up paying more after canceling your order and re-submitting it at a new height or lower price. If a market is fairly stable then limit orders are a great way to get a trade settled for the price you are looking for.
If you want to learn more about orders you can check out stock trading tutorials