"relation" vs. "relationship"

I assume that “relation” refers to things while “relationship” refers to people but I don’t know that for sure.
Would you kindly let me know the difference between “relation” and “relationship”?

Both “relation” and “relationship” can refer to both people and things, but they have several somewhat different meanings. The Longman Online Dictionary is a very good resource. It explains both words very well, and it gives good examples. You can reach it here: ldoceonline.com/

Thank you very much for your advice