Vintage Modified has a maple fretboard and block inlays, of course, and the Classic Vibe has a rosewood fretboard and dot inlays...different bridges, but other than that?
From my personal experience, better build quality and sound. I've tried out a couple of dozen VM's and owned a couple of CV's. The VM's have yielded a few excellent ones, a few "barely meh" ones and a lot in-between. The CV's have either been "damn good" or "super awesome". So are they worth the extra bucks? I say, you bet yer a$$ they are! Here's another way to look at it…the Classic Vibe's represent Squier's premier line. It's unveiling also coincided with Fender, along with Squier, in upping their collective quality control. The CV's became both the recipient of that upgrade and the bearer of that hallmark.
I have owned several CVs and many VMs. The VMs of many years ago are not like the newer ones. The CV basses all kick major butt and beat the pants off anything MIM. I actually play out with the white CV jazz bass as a secondary tuning bass (with upgraded tunes and DiMarzio pickups). The core of the bass to me is 90% of my MIJ Geddy Lee Jazz. The classic vibe stuff - in my opinion - is the best deal for a working musician wanting top quality on a budget.
"The VMs of many years ago are not like the newer ones." Please explain Michael Rogers... When I got back into playing bass 8 years ago I bought a used Squier VM Jass 70's bass from Talk Bass. By far it is one of the nicest basses I have ever played. With all the talk of the new CV Jazz bass..I ordered one for my local Mom/Pop music store. The CV sounded great and looked great too but for me the satin finish the VM's neck was a big plus compared to the thick glossy finish on the CV Jazz. I still have that older VM Jazz with that satin finish neck...the CV I traded for some thing else. I do have a Geddy Lee Jazz to which I do like very much the neck finish is not finished as thick or "orangy" as the CV was but to me feels great. I now own a Modern Player Tele Bass which I just love.. To me it is a great bass and in some ways a step up from the Squier CV line...but that older VM 70's Jazz still holds a special place in my heart.
I bought a CV Jazz in Inca Silver a month ago. Easiest thing in the world fixing the glossy neck problem...only takes a few minutes to make it smoother. Regardless, I like both versions, but wasn't exactly sure why the CVs cost more. A few more color options would be nice for both lines, of course. Upgrading both models is something many people do, and I'm considering Super 55 pickups. It's always nice to be a little bit different, whether it's adding better strings, a different pickguard, or a bridge and pickup cover.
With all the talk about "Glossy vs. Satin finishes" it's worth mentioning that some of the newer VM's also have a glossy neck finish. I know Squier has been doing it for the 2014 models, but I can't remember if they started it in 2013 or not. Can anyone with a 2013 VM Jazz chime in?
My VM is 3 piece basswood body with sunburst, rosewood fingerboard, no inlays. Those seem to still be available. No complaints about fit or finish, tuners smooth and stay in tune effortlessly. The Classic Vibe basses seem to have a slightly higher mass bridge with brass saddles, plus cool color options not available in VM like Inca Silver. CV necks have a more vintage yellow high gloss finish. To contrast, my VM neck has a no tint, satin finish, like they just barely sealed it and shipped it out. Very similar to the lower end squiers, though the neck itself has no problems.
I have a VM 70's Jazz neck that was on a MIM Precision body. The finish is glossy not the earlier satin finish (2013 date),,but no where as thick and "sticky" as the finish that was on my CV Jazz.
IMHO the CVs are worth the extra dough. Still struggling a bit with my VM Jazz, still looking for "the sound" in my head when I play it. Great bass though. My CV P Bass is winner straight out of the box. I'd say drop the extra $$ for a CV that speaks to you.
I have a '13 VM Jazz and its satin. Also, my VM Jazz plays much more nicely than my '04 MIM P Bass...
PUs are voiced differently (as per their era designation) CVs are basswood - VMs tend to be agathis or maple depending on model..(other than the VM TB which iirc is basswood under a veneer) MIC vs MII Standard vs HiMass Bridge aesthetics
Strictly comparing a Squier CV 60's jazz to a new VM 70's Jazz (maple): The VM bass was A LOT lighter and the neck felt skinnier. The CV had better hardware - at least as far as the bridge goes. Both are high gloss (again, current versions) and sound great. The VM was brighter & a little thinner sounding - prob because of the soft maple wood. The CV may have had more output.