Deepali Bhardwaj

Lemmatization typically refers to doing things correctly with the use of a vocabulary and morphological analysis of words, with the goal of removing only inflectional ends and returning the base or dictionary form of a word, which is known as the lemma.

The purpose of stemming and lemmatization is to reduce inflectional forms and occasionally derivationally related forms of a word to a single base form. The two terms, however, have distinct flavors.

Lemmatization is commonly used to describe the morphological study of words with the goal of removing inflectional ends. It aids in returning the base or dictionary form of a word, known as the lemma.

https://blog.bitext.com/what-is-the-difference-between-stemming-and-lemmatization/

https://nlp.stanford.edu/IR-book/html/htmledition/stemming-and-lemmatization-1.html

While converting to root-form, lemmatization always preserve the dictionary meaning of the word.

I guess you will have more explanation from here.. Steve Baker, an engineer in the search quality group at Google, just did a nice post about synonyms on the Google blog.

https://googleblog.blogspot.com/2010/01/helping-computers-understand-language.html

And this guy has summarised it,

https://www.mattcutts.com/blog/google-synonyms/