An order is a way to express an intention to execute a transaction. It specifies the instrument, operation direction, quantity, and price conditions. The latter determines how the instruction will be executed.
A market order is executed immediately at the best available prices in the order book. It guarantees transaction execution but not price: with insufficient liquidity, execution may occur across multiple levels and the average price may be worse than expected.
A limit order contains a price limit: buy no higher or sell no lower than the specified value. It protects against unfavorable prices but may remain unfilled if the market doesn't reach that level.
The choice between them depends on the instrument's liquidity. For securities with a tight order book, the difference between the two types is minor. For thinly traded ones, it's significant: a market order on an illiquid security may execute at a price notably different from the last trade. In the Uzbek market, where liquidity is unevenly distributed, a limit order is often the more reasonable default choice.