The devices, dubbed the G915 Lightspeed and G815 Lightsync, boast one major feature: an "impossibly thin" and "ground breaking" design, coming in at just 22mm. Logitech calls this a "feat of engineering," which is debatable -- true, there aren't exactly hundreds of ultra-thin gaming keyboards on the market (not high quality ones, anyway), but they do exist.
Anyway, Logitech goes on to say that both the G915 and G815 are crafted from premium materials, with brushed aluminum top plates, and "low-profile" keycaps that show off a bit more of the keyboards' fancy RGB lighting.
Both boards will ship with one of three switch variants: GL Clicky, GL Tactile, and GL Linear, which function pretty much how their names suggest. Clicky offers loud and tactile feedback, tactile is a bit quieter with only a "gentle" feedback bump, and linear is completely smooth.
Design and function-wise, both keyboards are almost completely identical. They offer the same per-key RGB and macro customization (as well as five rebindable "G-keys" toward the left), and the placement of various buttons and switches are similar.
The key difference lies in their connectivity: the G815 is wired, whereas the G915 offers "pro-grade" wireless functionality, with a 1ms response time and 30 hours of battery life (at 100 percent backlight brightness) on a single charge. Recharging will take about three hours in total.