A Special Economic Zone (SEZ) is a designated duty-free enclave treated as foreign territory for trade, differing from Export-Oriented Units (EOUs) that can be located anywhere in the country. SEZ units can be established for manufacturing or service provision, with incentives like duty-free imports and tax exemptions, and must achieve positive net foreign exchange earnings. The approval process for SEZ units is managed by a unit approval committee led by the development commissioner, and units can exit after a fixed period of five years.