The difference is that entangled particles cannot be modelled using a local hidden-variable theory of quantum mechanics (that's what the Bell inequalities and experimental evidence have shown). The reason why this is the case is a more involved question which I tried my best to explain in [1].
So entangled particles give you fundamentally different properties to a seed to an RNG (or any other arbitrary local hidden-variable setup you can come up with).
So entangled particles give you fundamentally different properties to a seed to an RNG (or any other arbitrary local hidden-variable setup you can come up with).
[1]: https://news.ycombinator.com/item?id=22490693