The rear seatbelts optional on the S-Class inflate when a collision is detected, helping to spread crash forces over a much larger area of the body and limiting head and neck movement. This can help prevent spinal and internal injuries. The G90 doesn’t offer inflatable seatbelts.
The S-Class has standard Post-Collision Brake, which automatically apply the brakes in the event of a crash to help prevent secondary collisions and prevent further injuries. The G90 doesn’t offer a post collision braking system: in the event of a collision that triggers the airbags, more collisions are possible without the protection of airbags that may have already deployed.
Earlier warning of stopped traffic, traffic signals, dangerous road conditions, weather, or accidents, can keep driver's safer and prevent crashes. The S-Class has Car-to-X Communication, a system that seemlesly communicates important warnings to the driver about impending danger, if they're available. The G90 doesn’t offer a system that can receive automated systems from infrastructure or other vehicles.
Both the S-Class and the G90 have standard driver and passenger frontal airbags, front and rear side-impact airbags, driver knee airbags, side-impact head airbags, front and rear seatbelt pretensioners, height adjustable front shoulder belts, four-wheel antilock brakes, all wheel drive, traction control, electronic stability systems to prevent skidding, crash mitigating brakes, daytime running lights, lane departure warning systems, blind spot warning systems, around view monitors, rear cross-path warning and driver alert monitors.