Well, a trailing stop follows the security up, changing your sell point step by step. If (when) the security you're trailing backs off to the point you preset, either a percentage or amount, it triggers a sell order. For example: You purchase a stock @ $10 PS and you set a trailing stop of a dime (actually it can be any amount you wish), at that point you have a sell point of $9.90. But, let's say the security rises .50 and now has a last of $10.50, your sell point in this example becomes $10.40. Meaning if the security stops going up and actually backs down to $10.40, a sell order is triggered. If it only backs off .09, the sell is not triggered. Then if it rebounds to say, $10.51, it sets a new sell trigger to $10.41. A trailing stop follows it up infinitely, but will not let it drop past your stop point.
A limit simply says Sell my stocks at this price and nothing less. You might get more, but not less, thus a limit.
Hope this helps good luck and have fun!