What is the difference in Fluent between absolute pressure and total pressure???

absolute pressure = static_pressure + operating_pressure total_pressure = static_pressure + dynamic_pressure dynamic_pressure = 0.5*rho*U**2

absolute/gauge is just a reporting convention (usually relative to atmospheric pressure)

static/total is a key physical variation such that at rest static pressure = total pressure but as fluid momentum increases the two separate and the difference is the dynamic pressure.