As discussed, two very different experiences, so a bit of an apples to oranges. Aside from that, I would say the biggest difference between the two is that you're able to "play" Vegas to a larger degree than you can "play" WDW.
Vegas is going to be as expensive as you want it to be; but it doesn't HAVE to be. If you WANT to stay on the strip in the best properties and if you WANT to see select high end shows and you WANT to eat at the celebrity restaurants - - yup - - you could out-price The Mouse.
We don't even come close to matching our Vegas cash outlay to what we spend to go to WDW. Not even close. And we're not within ballpark view of high roller status.
It's all about watching for deals that are, in fact, legitimate deals. More so there than Disney Deals.
You go to Vegas the first time, you sign up for every player's club card you can whether you gamble or not to get on mailing lists. You pick up every freebee magazine you can when you're there because there are coupons in them. There are different newsletter member sites you can sign up for that may include coupons that will more than recoup what the membership cost.
We've seen a lot of shows and I doubt that I've paid rack rate for any of them. Between coupons or package deals I had going in, tix4tonight, or online discount sites, we've been able to save significantly. And quite often, a well placed Andrew Jackson or so will upgrade you out of the discounted seats into "prime time".
For example, we stayed at Encore once and did virtually no gambling. I've remained on the Wynn mailing list and continue to get room offers. This last one was for rooms in midweek for a price just slightly above what it would cost me to stay at an All Star. True they tack on a resort fee, but the deal included two free dinner buffets (a meal significantly different than a Disney-style buffet) and a free night if I came back in December.
Everybody that does Disney well plans quite a bit. You can do Vegas well (and cheaper) with the same planning effort.
But yes - it is an adult destination when you boil it right down - which is not going to be palatable for all.