A market order executes immediately against the best price available and is used when the speed of execution is prioritized over finding a lower price. As long as there are willing sellers and buyers, market orders will be filled.
A limit order allows a trader to specify an exact price and quantity to buy or sell.
Example: If the current market price is 250 and you would like to buy at 249, you can place a limit buy order at 249. If the price hits 249, your limit order will be executed at 249 (given that a match can be found).
A stop-limit order is a buy/sell order which combines the features of a stop order and a limit order. Once the stop price is reached, a stop-limit order becomes a limit order that executes at a specified price (or better).
Example: If a trader wants to buy once price reaches 250, but not pay more than 252, a stop price of 250 and limit price of 252 can be specified at the same time. If the price reaches 250, the order is triggered and will match best available asks up to 252.
What fees do I pay on Coin163?
An overview of the Coin163 fees can be found here.