lesser / lessor are similar-sounding terms with different meanings (referred to as homophones). To better understand the differences, see below for definitions, pronunciation guides, and example sentences using each term. 👇
lesser: (adjective) of less size or importance. (adjective) smaller in size or amount or value.
lessor: (noun) someone who grants a lease.
lesser: l·EH·s·er
lessor: l·EH·s·er
(Examples are Wikipedia snippets under the CC ShareAlike 3.0 license. Definitions drawn from WordNet.)