It'd be nice if you could come as well to have a final drink with me!

It'll be nice if you can come as well to have a final drink with me!

What's the difference between these two sentences?

Does the first one imply that it's unlikely the invited person will come or is it just a more polite way of saying the latter? And is this considered a conditional sentence?
pleasehelpWhat's the difference between these two sentences?
The meanings of these two conditionals are nearly identical. Ninety-five times out of 100, people will choose the first one.

It's hardly worth the trouble to discuss differences, they are so slight. Nevertheless, the probable reason that you hear the first more often is that the construction with would is more "remote". It's less pushy. It leaves it up to the listener to decide whether to come and have a drink without any pressure. That makes it more polite. If the speaker says It will be nice, he speaks as if the listener has already decided to come and have a drink. It doesn't leave the decision to the listener quite as much. That makes it less polite.

On the other hand, the version with will could be interpreted as more encouraging rather than as less polite. So much can be done with tone of voice that the voice inflections themselves can override the exact words that are chosen. This is why the differences turn out to be so slight. Discussing the slight differences in word meanings in this case amounts to "operating below the level of the noise".

I don't think the choice has anything to do with how likely it is that the invited person will come. He will decide for himself in either case.

At a first look, I would think the same you did first: in the first sentence the speaker is not sure about if the invited person will come, or at least much less sure than in the second case. They are just two kinds of conditional sentence: the second one looks much more like a first-conditional one. (You could check on an english book, try looking for "first conditional" "second conditional" and "third conditional")

The answer to the second question is yes: both sentences are considered conditional. (The key word is the "if")
 CalifJim's reply was promoted to an answer.