The way this resistance is modelled differs from vector to raster. Using vector, it is easier to import the attribute data of a given network in from an external database, which is where the data often would be stored in real life. Directions over a raster network cannot be carried out without first deriving the topology from the surface properties, whereas directions are an explicit part of the vector topology, even when they need to be corrected and validated in the modelling process. The vector model can hold discrete entities, for instance keep the exact length of an arc as arc attribute, while the raster model only will approximate this, depending on the grid resolution. In vector, due to coordinate referencing, there is virtually no limit as to how close lines can be or how many that can be incorporated in the network.
Computations are very much based on the same principles.
It does not, like in raster, constitute a large number of interwoven layers. The vector data model is feature oriented, as it represents space as a series of discrete entities, which are geographically referenced by Cartesian coordinates. The raster model is location oriented, where each cell is part of a tessellated continuous surface that describes a given attribute. Since a network is based much more on the interaction of its component entities than it is based on its component locations, the vector model intuitively seems more appropriate for any kind of network. A raster-based network model, on the other hand, seems to be more fit, when the problem is concerned with finding a path across terrain that does not have predefined paths, and where the network does not consist of many attribute layers and artificial directional constraints, because that will make the modelling process more complex.