Difference between normal eye contact and an eye fuck?

So I've been experiencing some pretty intense eye contact from a guy recently but it got me wondering... what exactly is the difference between normal eye contact and a full on eye fuck?

For example, today during conversation, a guy made constant eye contact with me and it was me that was tending to break that when I started to also address the other person. I didn't for one money consider his eye contact to be sexual on any way.

However, there's this other guy and when he looks at me it's like he's transmitting secret signals to me and I can read his mind and know exactly what he's thinking (and it involves me with no clothes on ;-) !!).

How do we actually tell the difference?
Difference between normal eye contact and an eye fuck?
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