fail to as not do or not succeed?

[keannu]

"Fail to" seems to have to meanings of "not do" and "not succeed" How can you tell the difference? The following seems to mean "not do", but "not succeed" at the same time.
ex)You will be sorry if you fail to save for the future.

[keannu]

This would be confusing even to native speakers, I guess.

[Raymott]

"Fail to" seems to have to meanings of "not do" and "not succeed" How can you tell the difference? The following seems to mean "not do", but "not succeed" at the same time.
ex)You will be sorry if you fail to save for the future.

The context will generally give the meaning.
Generally, failing or not succeeding implies an attempt. But that's not necessarily true. You can fail in someting because you didn't try.