SWAT can manipulate and analyze many hydrological and agronomic data in order to predict the effects of land management on water resources. It simulates transfers nutrients, sediments and pesticides to the drainage network and to aquifers. SWAT also simulates crop yields in the presence, according to environmental conditions and cultivation techniques.
Watersheds represented in this model have areas ranging from hundreds to several thousand km². The model takes into account the entire hydrological cycle, represented in the watershed spatial manner. SWAT can analyze the watershed as a whole or by splitting it into sub-watersheds containing the same portions called Hydrological Response Units (HRU).
SWAT can be linked with the ArcGIS software. This facilitates the collection and use of the input data and manipulation of integration phases and calibration.
As for the Rusel model, honestly I have no information.