What is the difference between a guy checking out a girl vs a guy always wanting to hangout with a girl?

If a guy checks out a girl but isn't putting in effort to hang around her is he interested in her? Or is he interested in a girl with whom he wants to hangout all the time whom he also finds attractive?

What's the difference between the two scenarios?

Updates
2 mo
I think people are confused as I said in the second also the guy finds the girl attractive they are not "friends" there is romantic interest
What is the difference between a guy checking out a girl vs a guy always wanting to hangout with a girl?
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