Estimation or kriging-like techniques
These techniques are dedicated to the mapping of the phenomenon in between data locations. The variogram is used to provide a safe path between data points. Safety comes at a price: the estimated profile is usually smoother than the unknown real one.
Conditional simulation of the unknown reality
These techniques are used to characterize the uncertainty on estimates (oil volumes, grade above cut-off, pollution risk). Simulations reproduce the variability captured by the variogram. They offer a more realistic representation of the unknown reality. Realism comes at a price: safety. Each realization in the simulated model is a riskier estimate than the Kriged one above.