Galliu Sacca

you compress an WHOLE file in the ZIP with certain rules (it’s all inside the ZIP) and when you open it of course you will have a perfect file to the original ... as we know with the FLAC file you cut some frequencies (not audible etc...), and in fact you compressed the file... but at the time of conversion you have the weight of the original file, but it will never be as if it were the original file... you will have a WAV that will sound like FLAC

Of course I also have doubts because I can imagine how the ZIP keeps the original data of the original file before compressing, even the FLAC behaves the same way? Is that what you’re trying to say?

but then what I don’t understand is: why is there a MB difference? if the frequencies are cut? Wanting to agree, then the cut frequencies are compressed? where do they go if the conversion restores the original file?

The problem is that you think the difference between a "original wav" and a "restored wav" is the original audio data.  The difference can be the non-audio data, tags for example (title, author, year, cover, etc, etc, etc) lose in the process of conversion. Some FLAC encoders keeps the non-audio data, others don't do that by default. 

I will try to find more information to fill my gap... I seem doubtful about this topic, I learn your notions as a teaching, thank you!