Staring is when you’re not engaged with the person. Eye contact is to show that you’re giving your attention to that person.

It depends on the culture though. Some cultures don’t find staring rude.

Everyone's comfort level with recieving eye contact is different. I'm awful at giving eye contact, I've no VI. I'm great at looking at them while they are talking, but when I feel under pressure I look away loads.

I don't think there's a hard line, but some of the characteristic of a stare can be:

It's constant and unwavering.

Inscrutable facial expression.

Inscrutable body language.

It feels to the other person as if it's judgemental and scrutinizing.

Some characteristics of eye contact are:

Engaging facial expressions.

Engaging body language, including head movement.

I can't give you universal rules, just guidelines. If people know you're blind or visually impaired, they should factor that in rather than calling you rude.

I used to know a guy who, he wasn't blind, but he had a condition with his eyes where he always looked like he was looking a bit off to the side of you when he was talking to you. I never asked what the condition was, so I don't know. But I understood that's just the way he was and made no mention of it.

You sound like you have exotropia like I do. I cannot make eye contact if I wanted to, and get accused of staring or looking at things when I am not.

Now this may sound crazy but I have totally had students who don’t do the following. Blink. It may be that you are trying so hard to have eye contact that you aren’t blinking enough. Which can legit feel like a stare. You can also “look” away. Maintaining long term eye contact can become too much. It can be intimidating. Blinking really does help.

As long as the person is talking, it is considered eye contact and not staring. Assuming looking at their face of course.