a good gaming mouse would have more adjustable options to fit your hand whether you are left or right-handed or hold the mouse with different grips, they can also allow you to swap different surface materials for better comfort and ergonomics. Some mice also allow the addition of weights so you can tailor it to your personal preference. Comfort is important when you’re playing games as gamers tend to use the mouse at extended periods at a time. Having RSI or sore muscles is detrimental to e-sports performance.
a gaming-grade mouse tends to have better quality buttons that last longer, has more tactile click, better mechanical switches, and thus more consistency. This is important when you’re timing headshots or performing actions where a high degree of accuracy is required. The buttons are also programmable and can be used as macros that consist of multiple keystrokes, so the possibilities are endless as to what you could do with them. There are usually more buttons than a standard mouse too.
A gaming mouse has higher quality sensors with adjustable DPI on the fly, they have better capabilities such as response time speeds, able to sense faster acceleration and velocities than is humanly possible. Firmware and Memory – firmware can be upgraded and some have internal memory to remember personalization settings and macros. All of the above contribute to a slight edge over the standard mouse.
Also, they look cool and there are different designs to suit any gamer's taste.