Wildlife generally means non-domesticated animals that are large enough to see. It does not usually include microfauna or ranched animals.
Adapting the definition used by the ODP, Wildlife Ecology is a branch of science dealing with the interrelationships of wildlife with their own species and other animals, and with their nonliving environment. These relationships include physiological responses of individuals, structure and dynamics of populations, interactions among species, organization of biological communities, and processing of energy and matter in ecosystems.
However, as a science, Wildlife Ecology generally excludes fish and fisheries. Fisheries Ecology has developed its own tradition and methodology. The distinction of course is a convention.
Wildlife Management is included here because in practice, management is generally (though not invariably) based on ecological principles and knowledge. However it often incorporates an additional component of human interaction: it has been described as "a triad that includes habitat, people, and animals, and the interactions that occur between them" (See also: http://www.vetmed.ucdavis.edu/whc/Krausman.html.