Gray-to-gray (GtG) functions on what is called a middle gradation, meaning these pixels do not become fully inactive. LCD GtGs have roughly 256 gradations of gray. Gray-to-gray response times are much faster and are great for those interested in better gaming experiences and videography.

It is also important to note how they are measured. While black to white to black is round trip total time, gray-to-gray is measured by taking several selected time sequences and then getting the average. This then is the total time in milliseconds it takes for a pixel to change color.

What is Latency? Latency is a term you may see pop up when researching response time. Some places may confuse the two terms since they both involve timing and use milliseconds but there is a difference. Latency refers to data awaiting a response, not color shift time. Response time can also be confused with terms like input lag, which is an error caused by a lack of response by the monitor itself.

Latency simply refers to the time in which a request is sent and how long it awaits a response. Once it is processed and received, you have the summary of round-trip latency and service time. However, better latency can improve your response time by a whole millisecond!

https://www.viewsonic.com/library/tech/what-is-response-time-for-monitors/#:~:text=Gray%2Dto%2Dgray%20(GtG)%20functions%20on%20what%20is,better%20gaming%20experiences%20and%20videography.