What is the meaning of word form matching rather than concept matching in computer retrieval? For medical literature retrieval, what is word form matching and concept matching?

What is the meaning of word form matching rather than concept matching in computer retrieval? For medical literature retrieval, what is word form matching and concept matching?

(1) Simple keyword matching in word form retrieval, the results can be obtained after matching
(2) Concept matching belongs to the category of semantic retrieval, which can be simply understood as synonym and near synonym matching, that is, after inputting the key words, the system will search for similar concepts in the knowledge base according to the key words, and then search. This method is more optimized