the two both can express to have done something with different emphases. 了 emphasizes recently, just now, already, etc. e.g we often ask each other 吃(饭)了吗? which means have you eaten food(had breakfast, lunch, supper etc). 过 emphasizes experience, once at least, ever before, etc e.g (以前)吃过吗?means have you eaten it ever before. hope that help.

了：it was used after the verd and Adjective ，Expression the movement or change is completion 过：have two mean. frist,from one place or time transfer the other place or other time。second,be used after the verd, mean the movement it Completion

了，it shows the various tone by the end of the sentence . 过，it means a action.