I presume you are referring to the scale setting in the *Population* vs. the object itself (tgo, obj, etc.) which is parented by the population.
The min/max scale settings in the population set a range of *variation* in scale that the resulting population instances will be rendered within. This range is expressed as a multiple of the *base scale* of the object - it is not measured in meters because it is a relative value, not an absolute one. If the min and max are the same, all instances will be of the same size. If the values are min 1, max 2, then instances will vary in scale between the base scale (defined in the object being instanced) and 2x the base scale. For example if the base scale is equivalent to 10 meters, the instanced objects will very between 10 and 20 meters.
The scale settings in the object itself are unfortunately also relative, but they are relative to an absolute baseline defined internally by the object. For objects generated by 3rd party programs such as obj's, the scale is determined in the application in which it is created. This scale, whatever it is, then becomes a base scale of "1" for each dimension, x, y and z. So for example of the modeling program used to create a car works in meters and you create a car 3 meters long by 1.5 meters wide, this will become a scale of 1 for each dimension in Terragen, but the relative scale will be maintained. So adjusting the base scale here is done in a relative way as well, and not measured in meters. Ideally the base scale would be absolute and measured in meters like other absolute values, but for now this is not possible.
In any case the most important and basic difference is that the scale in the object node itself defines a base scale for that object and all instances of it, relative to the scale it originally had, defined by the modeling program. The scale *range* in the population node defines a potential range of scale which is *relative* to the base scale set in the object node. This is to provide for "natural" variations that make your populations look more realistic, especially in combination with the rotation ranges.
- Oshyan
