Here's an example from my life which hopefully helps you: There is a guy that I'm friends with, maybe you can say we could have something more if I wanted to, but since I don't we're just friends. He is always there for me and we're very close. He's a special someone to me because if I were to ever lose him as a friend I would be very sad. Now, someone you love is someone special to you and on top of that you want a relationship with them. You want to be more than just their friend. I won't explain the other kind of love (family/friends) because I'm sure you're confused about someone you possibly could have a relationship with. But yeah someone special is someone you need and want around but nothing more and someone you love is someone you need and want around, plus you want to be with them.
When you say special, that means you love the person. But when you say love, that person might not be special to you. That's what I think.
You're special someone might not fully reciprocate those feelings versus the one who loves you, who does
I think if you say a person is special doesn't always mean you love them but if you say that a person is the person you love then that is your the someone you love
These no such thing as love it is believed by fools love is something you can never know only you can feel it