Wealth is possession of real assets, natural resources, real estate, valuable companies, in classical econ terms, any scarce resource. Money is not a scarce resource, for nearly marginal cost we could create a near infinite amount of it (and in the digital age of banking we often do create large amounts of it with no direct cost). You can't create more oil, land, houses etc without incurring considerable costs, whether it be in the form of effort, time or etc and that's what makes those resources scarce. Money is scarce if you look at it on a personal level, you can't just create more money for yourself, but that doesn't make it scarce on a global level.

What might create some confusion is that wealth is often measured in money, but that doesn't make it the same thing. Wealth is real resources and money is the means we use to decide who gets how much of those real resources.