Constitute and comprise are close in meaning, but they point in opposite directions.
Use constitute when the parts make up the whole. In other words, the members, ingredients, or sections constitute something larger. Example: Five departments constitute the new division.
Use comprise when the whole includes the parts. The larger thing comprises its members or sections. Example: The new division comprises five departments.
A quick way to remember it is direction:
- Constitute: parts to whole
- Comprise: whole to parts
A common mistake is reversing them, as in The committee constitutes five members. Standard usage prefers Five members constitute the committee or The committee comprises five members.
If you want a simple test, ask what your subject is. If the subject is the parts, use constitute. If the subject is the whole, use comprise.