True. But that's got nout to do with why people get them mixed up.
Generally speaking, affect is a verb and effect is a noun. When you affect something, you produce an effect on it. Even in the passive voice, something would be affected, not effected.
There are certain situations where effect is used as a verb and situations where affect is used as a noun, but very few people ever have a need to use them thus, so unless you are already confident of your ability to use these words correctly, just treat as general the rule that effect is a noun and affect a verb.
(If you feel the need to get fancy, however, here are the meanings of effect as a verb and affect as a noun. As a verb, effect means to execute, produce, or accomplish something; as a noun, affect is used primarily by psychologists to refer to feelings and desires as factors in thought or conduct.)