My counselor says it's paranoia if it's not likely happening/going to happen and not based on previous events, and anxiety/fear if something similar has happened to you or is widely happening to other people. The example we talked about was being abused by someone. I was afraid it was going to happen again, and that was anxiety, not paranoia. Paranoia, however, was believing doctors were intentionally injecting me with deadly bacteria every time I got my blood drawn.

Sometimes the line is hard to define. People get followed, but I don't think it's very common especially with malicious intent of breaking into your house to harm you. Have you ever had something like that happen to you, or have you heard about it happening to someone else close to you or maybe it was in the local news recently? If that's affirmative, I'd say it was definitely more of an anxiety thing. Otherwise or without any other reason to believe such a thing was happening I'd say it's more accurate to call it paranoia.