How can a woman differentiate between continuous vaginal discharge (yellow and white) and madhiy and maniy, especially since this discharge does not cease?

The distinction between secretions is made by knowing the characteristic of each. If there is no sign indicating that it is semen (mani) or pre-seminal fluid (madhi), then the default is that it is normal vaginal discharge. One can refer to the fatwas related to how to differentiate between semen, pre-seminal fluid, and vaginal discharge, and what is required of a woman when they exit, or if she suffers from incontinence of one of them.