Usually in order for something to meet diagnostic criteria in psychiatry, the problem needs to be severe enough that it significantly interferes with a person's ability to function. Otherwise the features of the disorder are just "traits". So you can say that someone has borderline traits without having a full blown personality disorder. Another example: maybe someone is a little compulsive about handwashing but they are able to work and have friends and go out and not need medical attention for their raw hands and they can tolerate their anxiety if there's no sink nearby. You could say that they have obsessive-compulsive traits but they don't meet the criteria for the disorder.

I've noticed that a lot of T's play fast and loose with diagnostic terminology. IMHO this is generally to the detriment of the client. I think it's usually better, especially with personality disorders, to describe the problematic thought process, behaviour or pattern that it is to slap a label on it.