What I mean is would your brain, or mind be the same if you had a lucid dream about sky diving, as if you really did it? If that makes sence.
I dont know that i got it right.
If you dream about sky diving, and never did it IRL, brain is going to make it like you expect it to be. Expects in that case are air makes sound, a lot of things under you etc.
If you dream about sky diving any you actually did it IRL, brain is “replaying” every thing you remember from it.
If you have already sky dived in real life, then it would most likely be as close to the real thing as it gets. If not, then it would be like how you expect it to be, which might not be that far away from the real thing anyways. When i sky dive i get the falling sensation and such in my stomach, feel the wind and so on… I have never sky dived in real life, but i know the feeling of being in free fall thanks to theme parks.
well you could look at it in that when you are skydiving all YOU actually experience is your minds interpretation of certain stimuli and your conciousness receiving the interpretations, when you dream it is quite a similar situation, not the same but quite similar. 
What about having a nightmare. They say what dosnt kill you makes you stronger, but would a nightmare give you the same strength, as it would IRL?
Well it can improve your self esteem, but fighting a dream monster will not make you a better fighter. Just like lifting weights in a dream will not make you stronger. If you can do something like skydiving, then dreaming about can improve your RL skydiving, but you should not expect to know how to do something just because you dreamed about doing it if you have never done it IRL
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I would be very wary of trying out techniques I learnt in a lucid dream and then applying that to skydiving in real life! 
Yes, even though when you dream your brain send singals to your muscles as it would IRL but you are paralysed. The same neural paths are stimulated, as far as I understand.
The thing about dreaming is that you don’t have Physical reality to verify if you are correct in your assumtions about whatever you are trying to do. But if you have experience of the real thing of course your assumtions are based on that. The more experience you have the more likely your assumptions are to be more or less correct. You know your own body quite well, and you know normal gravity quite well and how they work together in normal activity. So you can for instance practise how to walk a certain way. You probably can’t practise double backflips from rooftops.
I have kind of skydived
I was at this huge Incan Temple And I jumped around 3 miles down into the temple stairs. That was the coolest exp. ever. It fell like when riding a roller coaster with air and with a really big falling sencetion. And of course i never skydived in real life.
That’s the thing about dreams, sometimes they aren’t even what you would expect.
Several times in dreams, but ND and LD I have taken flight. Obviously I can’t fly, so you would think that the mind would create the experience based on what you expect it would be like.
But with me, I expect flying to be cold, wet (clouds are basically water droplets) and involve air resistance. But I have never experienced any of those in a flying dream.
So with dreams it can go either way, if you are lucid you could create all the variables and atmospheric things, but in an ND it’s really an open book. It could be like you expect but it could also be nothing like you expect.
[color=darkblue]It is obviously to do with what information is already in your brain. If you expect it a certain way and it turns out different that just means your SC doesn’t agree with your waking mind, since in dreams the SC is involved.
You may think that a flying dream should be wet based on you waking mind and knowledge, including reason and logic.
The SC works differently. When dreaming what you waking mind expects and what your SC expects are two different things…[/color]
Hmm…this raises a thought. Most people i know have had the falling nightmare once or twice, so when someone goes skydiving do they expect a feeling similar to their nightmare?