Replace vs. Substitute

'Replace' refers to the act of removing or taking out something and putting a new or different thing in its position. It implies a permanent or long-term substitution where the original item or person no longer works or is missing. The focus is on finding a suitable alternative that takes the exact place or functions as the original item or person. 'Substitute', however, is not long-term or permanent like 'replace' and refers to the act of temporarily using or employing something or someone as a stand-in for another. It implies a short-term solution where the original item or person may be unavailable for a while but will return or resume its role afterward. The focus is on finding a temporary alternative that can fulfill the function or purpose of the original item or person until it is available again. Here are some examples:

Both 'replace' and 'substitute' are transitive verbs. They can indicate that a subject used or exchanged one thing in the place of another, or that the subject acted in the place of another entity. However, in the second structure, 'replace' takes a noun phrase as its object while 'substitute' takes a prepositional phrase with 'for' as its object.