Think of the verb 'to confuse'. If A confuses B, then A is confusing (present continuous) and B is confused (passive voice). All adjectives ending in 'ed' or 'ing' are derived from the continuous or passive forms of a verb respectively. If you look at what the original verb is, you can figure out which adjectives to use every time.

both of them have different meaning i think 1- interesting : means something enjoyable or amusing 2- interested :means to have curiosity of something or pay attention to it