@jmakishe,
Of what models are you speaking, theres hundreds of geo models out there. Each has a different base and approach
Like, if youre doing some geophysical modeling, sometimes youd adopt an expqnsion approach, other times youd use discretization. Some models are orthogonal, others are variable, others re 3 D.
Many times we make runs at slightly different vriqbles and iterative inputs and compare the outputs.