Hello Melody, The 3 words could have distinguishable meanings but when their meanings are near the differences are as follows: *When something changes it goes from a state to another, yet does this gradually holding still many aspects of the primary state. *When it transforms the change is drastic in most aspects that you could hardly recognize the primary state. *When it varies it doesn't necessarily change but it holds many different diversified aspects at the same time. Examples: The color changed ( it became darker or lighter ) The color transformed ( became almost another color) It varies in colors ( comes in many colors ) He is not the same ,he changed ( some aspects of his character are not the same) He is totally transformed ( changed drastically * usually for the better*) I hope the difference between the words in their close meanings is obvious to you now :)

Dictionary definition of 'transformation' 1. The act or an instance of transforming. 2. The state of being transformed. 2. A marked change, as in appearance or character, usually for the better. 3. Mathematics. 1. Replacement of the variables in an algebraic expression by their values in terms of another set of variables. 2. A mapping of one space onto another or onto itself. 4. Linguistics. 1. A rule that systematically converts one syntactic form or form of a sentence into another. 2. A construction or sentence derived by such a rule; a transform. 5. Genetics. 1. The change undergone by an animal cell upon infection by a cancer-causing virus. 2. The alteration of a bacterial cell caused by the transfer of DNA from another bacterial cell, especially a pathogen.

Dictionary definition of the verb 'vary' v. var·ied (-d), var·y·ing, var·ies 1. To make or cause changes in the characteristics or attributes of; modify or alter. 2. To give variety to; make diverse: vary one's diet. 3. To introduce under new aspects; express in a different manner: vary a musical tempo. v.intr. 1. To undergo or show change: The temperature varied throughout the day. 2. To be different; deviate: vary from established patterns of behavior. See Synonyms at differ. 3. To undergo successive or alternate changes in attributes or qualities: Foliage varies with the seasons.

'Change' is a verb. Dictionary definitions of 'change' a. To cause to be different: change the spelling of a word. b. To give a completely different form or appearance to; transform: changed the yard into a garden. 2. To give and receive reciprocally; interchange: change places. 3. To exchange for or replace with another, usually of the same kind or category: change one's name; a light that changes colors. 4. a. To lay aside, abandon, or leave for another; switch: change methods; change sides. b. To transfer from (one conveyance) to another: change planes. 5. To give or receive the equivalent of (money) in lower denominations or in foreign currency. 6. To put a fresh covering on: change a bed; change the baby. v.intr. 1. To become different or undergo alteration: He changed as he matured. 2. To undergo transformation or transition: The music changed to a slow waltz. 3. To go from one phase to another, as the moon or the seasons. 4. To make an exchange: If you prefer this seat, I'll change with you. 5. To transfer from one conveyance to another: She changed in Chicago on her way to the coast. 6. To put on other clothing: We changed for dinner. 7. To become deeper in tone: His voice began to change at age 13. n. 1. The act, process, or result of altering or modifying: a change in facial expression. 2. The replacing of one thing for another; substitution: a change of atmosphere; a change of ownership. 3. A transformation or transition from one state, condition, or phase to another: the change of seasons. 4. Something different; variety: ate early for a change. 5. A different or fresh set of clothing. 6. a. Money of smaller denomination given or received in exchange for money of higher denomination. b. The balance of money returned when an amount given is more than what is due. c. Coins: had change jingling in his pocket.

Melody, you can't learn words by own. You should learn them with context. There are plenty sinonyms, and most of them don't have difference, but they used slightly different.