“By, Next to and Beside” are prepositions of “Place and Movement”. In other words, where is something or someone? These three prepositions are a great example of different prepositions that refer to the same subject. Arbitrary preposition choices are made by everyone, everyday! The main idea with prepositions is to use them in an understandable way. As long as the other person understands what you are saying, that is perfect communication. Also? Fluent speakers of English often communicate the same thought two different ways. This is often done to help the listener fully understand what the speaker is saying.