The difference between affects and effects is quite simple. Affects is a verb that indicates that something has an influence on a person or thing, while effects is a noun that describes the result of a change. For example, a drug may have an affect on a person’s mood, while the effect of the drug is the change in mood. Another example is a change in temperature, where the affect is the change in temperature, and the effect could be the impact on the environment. In general, an affect is what causes a change, and an effect is the result of a change.