Is “endless” an equivalence of “never-ending”?

Question

I observe the following definitions in Dictionary.com:

endless

adjective

1. having or seeming to have no end, limit, or conclusion; boundless; infinite; interminable; incessant: an endless series of complaints; Time is endless.
2. made continuous, as by joining the two ends of a single length: an endless chain or belt.

And

never-ending

adjective

1. having or likely to have no end: never-ending worry.

Both definitions seem quite equivalent to me. Is there any circumstance when one should be used instead of the other?

To give a practical example: are these equivalent?

Thank you for your endless efforts on creating good content!

Thank you for your never-ending efforts on creating good content!

Answer 1

They are indeed similar in meaning and can be used interchangeably in most situations. However there are differences.

The central idea is that something that could be measured, for example time or distance, continues without bound. By extension we then apply the without bound to less obviously measurable ideas such as creativity or love.

When dealing with time or distance both endless and never-ending work well, it's pretty much a matter of taste which to use. Personally, when sitting listening to an over-long speech I would use "never-ending".

When dealing with more abstract ideas endless often seems better than never-ending

For example ngram shows "endless creativity" is more common that "never-ending creativity".

One other idea is that "endless" somehow focusses on exploring, being immersed in, the thing that is unbounded, whereas never-ending focusses more on the looking for the bound to that thing. Hence my preference for never-ending when listening to very long speech.

In your particular example I don't think either word quite work, because I think you are thanking for past effort rather than considering the (endless) future.

Thank you for your tireless efforts in creating this excellent content