The webster dictionary and the law

How is it that the definitions we learn in school from the webster dictionary are either different, contradictory, or mean something else, than the state and federal law definitons or statutues? How are we as US citizens suppose to know or follow laws we are not taught, the only thing we are taught is between right and wrong. Unfortunately the law doesnt know right from wrong it only knows the law. FACT did you know that in some states oral sex is illegal? in some states the doggy position is illegal. How is it that we have different laws in different counties, and states? That can really confuse people. There should be no laws on positons of sex, there should be laws on," if you commit murder, or rape you pay the time or price. That should be law!!! Not pay the price depending on if you did the crime the right way or wrong way.