T-Mobile G2x is rumored to be the American brother of the LG Optimus 2X. There probably won't be much difference between the LG Optimus 2X and the T-Mobile G2x. Both should have Tegra 2 dual-processors, 1.3 and 8MP front and rear facing cameras respectively, with HD 1080p video capture.
The G2x is T-Mobile’s version of the LG Optimus 2X, so it features the same exact hardware as the global version. Highlights of the G2x include a Tegra 2 mobile processor with dual-core CPU, 4-inch WVGA display, 8-megapixel rear-facing camera with LED flash and autofocus, front-facing 1.3-megapixel camera, 8 GB internal storage, 512 MB RAM, and support for T-Mobile’s 4G HSPA+ network.
The G2x also actually mirrors its interface out its HDMI port, which could be very exciting. Most phones with TV out ports restrict them to only a few apps, either out of lazy programming or because content owners are terrified about letting you play Netflix from your phone onto your TV. The G2x doesn't play Netflix - no Android phone does - but T-Mobile told me it will stream games, Web pages, and its full UI over onto a TV. Tragically, content-owner restrictions are still possible here - T-Mobile's streaming "T-Mobile TV" service is forbidden from showing on TVs.
Sadly, neither device is 4G.
Both are HSPA+ 14.4, a sort of intermediate level between 3G and 4G. Confusingly, T-Mobile calls both devices 4G, but they've also said that networks slower than HSPA+ 21 aren't 4G. I'm going to stick on the "not 4G" side of this debate and say that I got download speeds around 3-4Mbps in quick speed tests of the two devices.
