Thesauri and Subject Headings List 

Both thesauri and subject headings lists are vocabulary control devices, but they are used in different situations. The essential characteristics which differentiate them are considered in the following sections: 

1. Subject headings list fulfills the needs of pre-coordinate indexes, whereas  a thesaurus is designed to meet the specific needs of post-coordinate indexes. 
2. Thesauri generally contain terms that are  more  specific than those found  in conventional subject headings list, 
3. A thesaurus normally avoids inverted terms such as 'Psychology, Children'. 
4. The relationship display is more extensive in the case of thesaurus than in  the case of traditional subject headings list. Incidentally, some well-known subject headings list, such as Library of Congress Subject Headings and Sear's List  of Subject Headings, in their latest editions, have adopted thesaurus format and are, thereby showing the relationships existing between terms. 
5. The relationships between terms listed  in a thesaurus are not transferred to the indexes in" many cases. Dictionary catalogues normally provide  'See'  and  'See also' references linking the related subject headings. 

The above are some of the significant  aspects that  distinguish a thesaurus from a conventional subject headings list.