while working on an solution for another post and cross validating some sample data I noticed the Date&Time Difference node does not factor in nor provides the option to in-/exclude the start or end date.

That always results in a difference which can lead to miscalculations due to misinterpretations. I.e. by factoring in all days between 2023-01-25 and 2023-01-30 one could count six days but Knime, as the node correctly states, only calculates the difference (30-5).

thank you for the nice comparison of Date time differences.
The Date&Time Difference node can also calculate the time difference between two time stamps. If we calculate the time difference between 18:00 and 06:00 we would expect 12h. Our goal is to be consistent in that sense, also for Date- and Date&Time Stamps.
I hope that my answer has given you some context of why the node was developed the way it is.
Would you also see a use case of your feature request for formats other than the date?

Iâ€™ve added my vote to @mwiegand 's post as Iâ€™ve also considered it would be useful to have the option of including and excluding the start and end.

Yes, probably Iâ€™d use it mostly for dates, but no harm in just making the option available, with it defaulting to â€śdifferenceâ€ť rather than what I guess is â€śtotal number in rangeâ€ť.

Dates are certainly a special case, in my view, and the use cases Iâ€™ve seen on the forum can be things such as:

â€ścount the number of days workedâ€ť

given a date range for which youâ€™d typically want an inclusive range as it marks the beginning and end of a work period.
(e.g. If I work from Monday to Friday, I consider that 5 days and not 4 no matter what my boss thinks of my work ethic on a Friday ! )

â€śCalculate the number of days it took to deliver an orderâ€ť

given a date range, for which youâ€™d typically want an exclusive range
(e.g. ordered Monday, received Friday - I would consider that to be 4 days)

So for dates, to me I can see very common use cases both ways, and having to keep throwing in a Math Formula node to do a (plus one) nigglesâ€¦ especially if itâ€™s on a friday!