You'll notice 16-bit looks a bit more greener (RGB565 - extra green bit to make it) in addition to the banding and dithering.

Games designed for the Virge generally go for 16-bit color anyway, even though it does have 24-bit color support...

Voodoos (until the 4/5) will ALWAYS be in 16-bit color no matter what, though the cards are known to try and mask this appearance with excess filtering.

Even native 24-bit frame buffers fall short of providing a banding-free viewing experience on a high-contrast display. A disturbingly high amount of people seem to think that dithering is an obsolete practice in the year of our lord 2019. It's of course not as crucial as it is with 16-bit color depths, where naïve rounding will defile your visual cortex.

by the sound of it, it doesn't make too much of different cause i am using a crt monitor and is it better to set my resolution to 16-bit colour rather than 24-bit colour

cause i know a few games where i will have manually change it from 24-bit to 16-bit or even lower than that like 256 colour for it work like

resident evil 2 (1998)
when using voodoo, the movie files will not play at all, if the "2D" card is set to 24-bit colour, you can turn off the movies in the game settings, the game plays fines but to get the game to play completely (movie files as well) - you need to set it 16-bit when using voodoo 1 card

titanic - adventure out of time
it ask me to change the colour depth to 256 colour when booting the game but after a windows 95 update (no idea which one - maybe is it quickres) it doesnt do that anymore

Basically true colour was a 'luxury' back in the early days of 3D acceleration. The extra processing power, memory and bandwidth requirements meant that it was not practical to use these modes, so gamers generally used 16-bit modes. PowerVR is an exception here, because its unique TBDR architecture means that it processes everything at 24-bit internally anyway, and the cost is much lower than with conventional accelerators.

ok so either one would be ok since i prob wont noticed the different too much

You'll probably notice that 24-bit results in a massive drop in framerates, and might even make your system go out-of-memory.

ok, framerates, not noticed too much and out memory issues - never happened