ENG or Electronic News Gathering, describes a style of production used in the aquisition of news for televsion. This particular genre is characterized by a small crew, sometimes one-man-band or otherwise a camera person and an audio person.
The equipment designed to be used in this environment is lightweight and simple and the kit is made up of a camera with a built in servo operated zoom lens, tripod, on-board camera light, portable light kit with stands and audio gear including shotgun, lavelier and probably several radio mikes.
The next step up the production hierarchy is referred to EFP or Electronic Field Production, where the crew size is usually bigger, to include lighting and grip technicians or an assistant camera person (like in film) and/or a boom operator to assist the audio mixer. The gear is often more sophisticated to include remote camera control and a monitor bridge of waveform vectorscope and large master monitor.
EFP production can also be found in the news environment, but more likely at the network level in the production of news magazines or other feature-type programs.
Both of these terms have are used to describe the scale of the type of production intended; because as we all know, no one wants to describe their show as a bare-bones cheapy, in that case "ENG-style" sounds a lot better!