each guitar sounds different from another. In fact, they are very unique.
The new Axis sounds brighter because it hasn't been played at all. The more you'll play it, the better it will sound
It could be that the strings are new, the frets aren't dull or worn down, and dirt and oils from playing aren't on the frets or pickups. The wood to to your older Axis may have changed just because of your areas climate. It could be a lot of things I guess.
Arno5150 is right though, every guitar is different!
I have a 2012 and one that's a few years older as well. The newer one is a lot brighter. I figured no two pieces of wood are the same so they will all sound a little different but, it will be interesting to see if it changes over time. I kind of like them that way since they both sound great but a little different.
I have 2 axis guitars as well. A 1996 and a 2000... They sound totally different! Guess that is why I can justify having 2 identical guitars (sans color) however, I can't say that I recall the sounding any different than the day I got each one.
I agree about the wood...no two pieces of wood are the same hence no two guitars will sounds exactly alike. I like that fact that each of my guitars has their own voice.