Alphabets are like atom, acronyms are like molecules or supramolecular assembly , words are like cells , sentences are like tissues , paragraph are like organs , chapters are like organ system , human or organism is like book and the group of books is like group of persons or community .

Different alphabets are like different molecules ,
Different words are like different cells
Different sentences are like different tissue
Different paragraph are like different organs
Different books are like different persons as they differ in appearance , colour , size , shape etc.