Qual è la differenza tra If we meet at 18:30 , will THAT be okey for you? e If we meet at 18:30 , will THIS be okey for you? ?Sentiti libero di rispondere con un esempio.

@alexandrabaku

In this case there is no difference in meaning.

This and that are the two demonstrative pronouns. The difference between them is really only useful when you are talking about how close or far away things are from you.

What is this worth? – This, because it is close to you – you are holding it in your hand.

What is that funny looking thing? - that, because it is on the other side of the room, far away from you.

I have never been to this place before – this place, here, where we are.
I have never been to that place before – another place, some distance from here, not where we are.

However, when we use the demonstratives in relation to things that don't actually relate to distance, we can usually use either one without any problem. Basically, it doesn't matter