Help Difference between URP shaders for v5.6.2?

[zkkzkk32312]

Hello,

I am new to using Obi Fluid v5.6.2 in URP in 2019.4+,
I notice that there are 3 different URP shaders

-FluidShaderURP
-ParticleShaderURP
-SimpleParticleShaderURP

I tried to playing with all the example scenes by using the above 3 shaders on the emitter and noticed only the particleShaderURP would actually render
My question what are the difference between them and when should I use the other 2 shaders?

Thank you