Simplify the following text for a Grade 7 native English-speaking person.
Original: The supermarket chain operates three main store formats ; regular Sainsbury 's stores ( ` Main Mission ' ) , Sainsbury 's Local and Sainsbury 's Central ( convenience stores and smaller supermarkets in urban locations - ` Mixed Mission ' ) and Sainsbury 's ` Main Plus ' ( hypermarket ) stores . Unlike Tesco ( Tesco Extra ) and Asda ( Asda Wal-Mart Supercentre ) , Sainsbury 's does not employ a separate brand for its hypermarkets , having phased out the ` Savacentre ' fascia several years ago .
Simplified: Sainsbury 's is the third biggest supermarket in the UK ( behind Tesco and Asda ) .