Hey Arosemond,
As the guys are saying, there's more to it than that.
If you set two completely different mixes so that they both peak at X, they may not sound the same level to your listener.
Our ears aren't equally sensitive to all frequencies.
A bass note and flute note peaking and sustaining at the same levels will not sound the same volume to us.
If one song has an attacking shaker with stray peaks the whole way through it, the rest of the song is going to sound quiet to us because those peaks prevent you from turning the whole thing up any further.
Then say you use a super fast compressor or limiter on that shaker to tame those peaks, all of a sudden you have room to turn the whole song up some amount with any huge tradeoff. See?
For perceived volume you're better finding a way to monitor average volume and for adjustments you're better thinking in dynamic range, which compressors and limiters reduce.
All of that said, if you have multiple tracks from the same band in the same room with, give or take, the same instrumental arrangements, things *should* work or, at least, they shouldn't be a million miles out.