The Lenovo can run Arma 3 at Ultra and very high settings with 25-32 fps, so it will run rust, probably not Rust: experimental version, as the experimental version is not optimised that well.
HP: I couldn't get an exact benchmark, but it seemed a bit choppy when playings games significantly less demanding than the Arma 3, so I, personally would go with the Lenovo (keep in mind that both games were recorded with fraps and the frames can drop by about 20 when using that program)