Welcome, Mottom.
Yes, the "Ti" designation is an older one. Very good speakers, and there are many "Ti's" out there. Axiom starting making some improvements here and there, and dropped the "Ti" designation, instead using V2, V3 and now V4. There were no "revolutionary changes, but more of an evolution with little tweaks of the drivers, crossovers, etc.
I still have M60 Ti speakers and like them very much. I haven't heard the M60V4s in a side-by-side comparison, but my understanding is that each generation has sounded a little more refined, and there would be a reasonable difference between my older Ti speakers and current V4 speakers.
