You use lesser in order to indicate that something is smaller in extent, degree, or amount than another thing that has been mentioned.
No medication works in isolation but is affected to a greater or lesser extent by many other factors.
任何药都不能独立地产生作用,而是或多或少地受到很多其它因素的影响。
You can use lesser to refer to something or someone that is less important than other things or people of the same type.
They pleaded guilty to lesser charges of criminal damage.
他们对较轻的刑事伤害罪的指控服罪。
You use lesser to indicate that someone or something has less of a particular quality than other people or things of the same type.
lesser known works by famous artists.
著名艺术家创作的名气较小的作品。