It's better to use batteries.
The battery capacity is generally about 1500mAh, and some large-capacity dry batteries are as much as 2500mAh, which is far greater than the capacity of the lithium battery built in the wireless mouse (generally 500mAh), so the wireless mouse placed on the battery is longer than the charging wireless mouse.
There is no difference in function, and the selling point is that there is no need to change the battery for charging. In fact, the wireless keyboard and mouse set consumes very little power, and a battery can be used for a long time. The cost of rechargeable batteries is only one investment away from the cost of ordinary batteries.
There is no difference in function, the selling point is that the charging does not need to change the battery.