Profit stop-loss for instance, is if I intend to earn US$100 take-profit, but the price has failed to exceed US$85 for several times, resulting in signs of reversal. In this case, the previous stop-loss should be adjusted (e.g. the a stop-loss of US$30) to a stop-loss of when there is a US$75 profit. This is to prevent profitable orders from turning profits into losses when profit forecast is not met, while still gaining partial returns.
Trailing stop-loss provides similar features. While the mechanism is the same as profit stop-loss, it is even more automated and convenient. When the price is moving in the favourable direction for you, stop-loss will be increased at the bank’s or broker’s server. For example, a stop-loss of US$30 with a book profit of US$20 will have a stop-loss position of US$10 loss. When the book profit is US$50, then the stop loss position is US$20 profit. However, the price will not reduce stop-loss when the price goes down. That is to say, if the market reverses when there is a book profit of US$50, your stop-loss is still at the position of US$20 profit. When the price limit is reached, it will acquire profits automatically and close the trade. The latter is more trouble-free and highly automated. But for experienced professionals who are on a full-on market watch, manual operation may be more beneficial for profits.