"substitute", "backup" and "reserve"?

[Nessie]

Hi,
Are there any differences among "substitute", "backup" and "reserve"?
(I think there aren't any)

Many thanks
Nessie.
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[Ralf]

Hi Nessie,

Is there any problem with a certain context you'd want to use these words in?

See you,

Ralf
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[Nessie]

No Ralf, I just came across them, then I looked up in my dictionary and felt that they are very similar.
_________________
... something we never have again, I know... I guess I really really know..

Sorry seems to be the hardest word...

[Alan]

Hi Nessie,

That's a broad question, isn't it? The words have a lot in common as they all point to the general idea of replacement. 'Substitute' can refer to a person who is standing in for another as in players in sport or for a thing used in food preparation because the 'real' thing isn't available. 'Backup' is often used in computing where material is kept back somewhere just in case the original material gets lost. 'Reserve' to me suggests most often the idea of someone standing by to take over when the usual person is unable to continue - again sport comes to mind. These are just a few ideas but no doubt the floodgates will open and you'll get loads more examples from others.

Alan
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[Yankee]

Hi Nessie

Here are a few examples:

We often talk about a 'substitute teacher' -- a teacher who temporarily takes the place of another teacher (e.g. because the regular teacher is out sick with the flu). I would not use 'reserve' or 'back-up' in this case.

You might make back-up copies of important documents on a CD. These copies could be used to permanently replace the ones located in your PC if your PC bit the dust, for example. (I would not use 'substitute' or 'reserve' here.)

You might keep some reserve cash hidden away in a cookie jar in the kitchen. This would be part of all of your cash, but this reserve is held somewhere away from the rest until it is needed for something out of the ordinary (i.e. for an unexpected or unplanned reason, or simply for something extra special). I definitely would not use the word 'substitute' in this case because this money in reserve does not replace anything. The word 'back-up' would not be a usual way to refer to this.
.