Element often refers to a chemical element (hydrogen, oxygen, etc). It can also be used to describe a situation or environment. "I was really in my element today." (This means that I felt good about what I was doing or that it went well.) It is less common to use this word for describing pieces, though it is possible. "Wood is a element of my house." This is correct and understandable but that information isn't usually conveyed that way. Constituent, the noun form of the verb constitute, literally means things that make up the whole. However, as a native speaker, I believe the only time I hear this word is referring to citizens represented by elected people. "The councilman went and spoke to his constituents." The verb is far more flexible than the noun in my experience. "Water constitutes the majority of this mixture." Ingredient is most often used in food related contexts. "Flour and butter are ingredients in this cake." or "Garlic is my favorite ingredient in my sister's mashed potato recipe." It can be used in other contexts but in general is used when a item is measured into other ingredients. "Respect is an important ingredient for a strong team." or "Gravel can be an ingredient in concrete." Composition is an outlier in this word list. It refers to the mixture of the whole, as opposed to a piece of the whole. "The composition of this song uses mostly major chords." "I thought your composition was made of studier stuff." It can refer to personalities, art work, writing, chemicals. It's a very flexible noun, but remember that it refers to the whole. There are other uses of some of these words but it seemed like your question was specifically about how to differentiate their similar meanings. I hope this cleared it up some for you!