"replace" vs. "substitute"

Question

When you replace somebody with somebody else, does it refer to a permanent change usually for a better one?

In "The company replaced Alice with a new secretary", does it refer to a permanent change?

What about substitute? When you substitute somebody for somebody else, is this change permanent or temporary? Like in a game when the coach substitutes a player for another?

I know you can say "The teacher was sick, so Jane substituted for her", and it means Jane is supposed to do the teacher's job until she's able to do it herself again.

Can you also use the structure with two objects to say that we put someone in the place of someone else temporarily until they can do it themselves again, in a sentence like "The teacher was sick so the school substituted Jane for her"?

Answer 1

These verbs both mean to put someone or something in the place of another. To replace is to be or to furnish an equivalent or substitute, especially for one that has been lost, depleted, worn out, or discharged:

To replace:

to provide a substitute for (something broken or unsatisfactory, for example) - AHDEL

To substitute:

To put or use (a person or thing) in place of another - AHDEL

While the two are synonyms, replace does carry a stronger connotation of being long-term.

The etymology of substitute, particularly the prefix "sub" may suggest why it has a weaker connotation of being permanent:

Origin

late Middle English (denoting a deputy or delegate):

from Latin substitutus 'put in place of',

past participle of substituere,

sub 'under + statuere 'set up'.

Substitute is rendered from it's Latin origin: "set up under"

PREFIX

1 At, to, or from a lower level or position:

subalpine

1.1 Lower in rank:

subaltern

subdeacon

Although permanent replacement is CURRENTLY an acceptable use of substitute, it's original use was closer to "deputy". A substitute would stand in for the principle as a duputy:

• a deputy "replaces" the sheriff who ordered him to execute the warrant
• the corporate vice-president "replaces" the president who is out of town
• margarine "replaces" butter when it is not available
• a temp "replaces" the secretary while she is on vacation

Each of those "replacements" is temporary because the principal remains available "above" her substitute.

Edited to add: As @John Lawler points out, they are the same but serve opposite rhetorical functions: he replaced 'old' with 'new'; he substituted 'new' for 'old'.