What would be the point at which you would distinguish between a Friendship and a Relationship?

So often, because people don't always think the same, and Friendships have so many levels, degrees and types, I think sometimes a person who feels the other person is his or her friend, is not thinking Friendship but Relationship? Friendships can be (Friend, Good Friend, Special Friend, Best Friend, yet none of those don't have to be considered a mate or partner). So with Platonic friendships and other types, with all the levels of friendships. With there being also an ociate, colleague, acquaintance and more. What in the world would make you say you have a relationship with someone. After all, when you communicate with someone you are "relating to them" but relating is not a relationship? Where do you draw the line?