Once

I read it as a woman and a man getting together to make music, him being very focused on making music:

"Here babe Are the notes you must play This babe, is the procedure"

Although he's possibly enamored with her too, or at least they have the relation of him calling her babe. 'Once' would be about maybe just one kiss, or making love one single time to just "get it out of their systems".

He's telling her she needs self-control (although it's not always clear where the border goes between the singer and the character, since they sing a-cappella in the chorus which I'd interpret as only her thoughts otherwise):

"If you can't control your mind Something will happen It's just a question of time"

But she says she can only control it for so long:

"Oh babe I can not concentrate I'm here for the wrong reason

It's you who makes my knees shake One season, then The brakes're gonna break"

Somehting like that?

I completely disagree with you.

Maybe in the way of them wanting one kiss, one night as a couple in love I can agree with that.

But,

For me this is a man and a woman who have shared something special as a couple, but with a shadow hanging over their heads.

"One season, then The brakes're gonna break"

It is the man who "break", leaving the woman with a promise that all will be fine.

"Here babe Are the notes you must play This babe, is the procedure"

He tells her this is how it have to be, this is the procedure.

"Hey you Can I breathe If my chest is covered"

She described the feeling of trying to understand/breathe but how is that possible if the chest is covered.

"Hey you Is my face making sense Eyes can't be still In a moment so tense"

This part I believe is when she gets the bad news, that he is leaving her.

She is in shock, moment so tense, eye's being still but thoughts and feeling rushing through her mind. Her face not making sense because of the difficulty of understanding what it means.

"Here babe Not in another way I can assure you That you will be OK"

He trying to assure her she will be okay, maybe promising her a new chance in the future.

"Once would do Once could change everything Once could tell And help me clear out Some things"

This part I have had a hard time figuring out, but I think it means one kiss, one more night together, one more day anything that will give them both what they need.

"Once would make No difference at all Once or not I've already made this fall"

This describes their feelings, that even if they stay together just for one more time they still have "given up", him by leaving her, and she is heartbroken and might never risk going back to him.

"Once would make No difference at all"

They know they already should have left each other, but they can't.

Something holding them back from letting go.

"Hey you Make the most of the time You've got to cross many borders"

He is telling her not to be sad, "make the most of the time" If she staying for just a little while longer, she should make the most what is left.

"you've got to cross many borders" She have to break boundaries to stay and to leave him she have to cross many borders.

"If you can't control your mind Something will happen It's just a question of time"

Its her that have to control her mind, she have to let him go. Not stay just because she hope he will change his mind and take her back. If she fails doing that, he might not want one more kiss/day/night.

"Oh babe I can not concentrate I'm here for the wrong reason"

She is giving up, she can't control her mind. She is there for the wrong reason.

Hoping for something that can not be.

"It's you who makes my knees shake"

Describing the feeling of love. Real love, she is aware now that it is over.

"One season, then The brakes're gonna break"

Reminding herself that this love was doomed from the beginning. But, still wanting more. Once will make no difference at all, but the whole "season"/"relationship" was only Once.

So what is the diference than?

This is just how I see this song, its the story of my life so for me this is what the song meaning is all about!

I forgot this part.

"Once could tell And help me clear out Some things"

They both want to have just one more moment before they separate, he want to clear out what he has done, why he feels he have to break them up. She want to clear out the same thing, how he can do that, why he want to end it.

They both holding on so hard, but still trying to let go of one and other.