Replace-Substitute | Commonly Confused Words

Replace

/rɪˈpleɪs/

To take the position of something or put something new in place of something old

Imagination has replaced reality.You talked to Gil Case about her replacing Terry King.Who replaces her Monday for the Philadelphia opening?"

/ˈsʌbstɪtjuːt/

A person or thing that takes the place of something or someone else

It was substituted for the other immediately after the murder.A substitute for a Fire.We each had a second bowl of the substitute rice.

Replace and substitute both involve a change, but they aren't always interchangeable.
Replace usually means to put something new in place of something old or damaged, while substitute often means to use something as an alternative, even temporarily.
You might replace a battery with a new one. But you might substitute sugar with honey in a recipe.
Remember, replacement implies a definitive change, substitute hints at a temporary or secondary option.
When in doubt, think: if the change is final and permanent, use replace; if its optional or temporary, use substitute'.