What is the difference between stop-loss market and stop-loss limit orders?

Both need a trigger price to activate, but they behave differently once triggered. A stop-loss market (SL-M) order, once the trigger price is hit, converts into a market order and executes immediately at the best available price, guaranteeing execution but not the exact price, which means it can fill worse than your trigger during a sharp move or gap. A stop-loss limit (SL-L) order, once triggered, converts into a limit order at a price you’ve separately specified, guaranteeing you won’t get filled worse than that limit price, but not guaranteeing execution at all if the market moves past your limit before matching. You use SL-M when you want certainty of exit above all else, accepting some price risk, and SL-L when you have a specific worst-case price you’re willing to accept and you’re okay with the small risk of the order not filling in an extreme move.