(a) Ancillary Industries manufacture components, tools, sub-assemblies intermediates and machines required by big industries like heavy electrical industry, aircraft industry, locomotives, buses, etc. For example, automobile ancillary industries provide supporting equipment like tyres, batteries, brakes, headlights, mirrors, etc.
(b) Public Sector Industries are owned and managed either by the Central Government or the State Government. They include public utility industries like railways, post and telegraph, oil refineries, heavy engineering industries, defence establishments, etc. For example, Bharat Heavy Electricals Limited (BHEL), Gas Authority of India Limited (GAIL), Indian Oil Corporation (IOC), Steel Authority of India Limited (SAIL), etc.