English is comprised of many confusing words. Or is it … composed of many words? Case in point: comprise and compose look very similar and have very similar meanings, so it’s no surprise that it can be hard to keep these two straight.

Let’s explore comprise and compose, how they are used, and how you can tell them apart.

The fundamental difference between comprise and compose has to do with the whole versus the parts of any object or concept.

Let’s take a closer look at the definitions to put this in context: comprise is a verb that means “to include or contain” or “to consist of” as in The pie comprises 8 slices.Compose means “to be or constitute a part of element of” or “to make up or form the basis of,” as in Eight slices compose the pie.

The key rule to remember is that the whole comprises the elements or parts, and the elements or parts compose the whole.

Their slippery meanings and similar sounds have likely contributed to the rise of “comprised of.” The argument against this phrase is rooted in the definitions outlined above. If we hold comprise strictly to the definition of “to include” or “to consist of,” then “comprised of” sounds awkward: The pie is included of 8 pieces sounds nonsensical, and, by that rule, so too does The pie is comprised of 8 pieces.To keep writers in the clear, style guides advise avoiding this construction and opting instead for composed of, consisting of, or made up of.

However, it is worth noting that “be comprised of” is recorded in dictionaries as synonymous with “be composed of,” and will generally get your point across satisfactorily in informal settings.