Question

Difference between density and relative density ?

Answer 1

Density:
Density refers to mass/volume
SI unit is : kg/m³

Relaltive density:
 relative density refers to density of a substance / density of water in 4°C  
 there is no SI unit

Answer 2

density has si unit relative density don't have si unit , density is in normal form relative density is in ratio with the density of subs is to density of water,