The same two dates, run through both calculators
From 14 September 2026 to 31 December 2026: the Days Between Dates Calculator (excluding the end date) reports 108 total days. The Date Difference Calculator, for the exact same two dates, reports 0 years, 3 months, and 17 days — which also works out to exactly 108 total days underneath.
Why the totals match exactly
Both calculators are counting the identical calendar gap between the same two dates — neither one is more "correct" than the other. The plain day-count calculator stops at a single number; the date difference calculator takes that same underlying gap and further breaks it into calendar-sized chunks (years, then months, then days).
When each answer is more useful
A single total-days figure is what you need for things like interest calculations, hotel night counts, or shipping timelines, where every day counts equally. A years/months/days breakdown is more useful for describing a gap in everyday human terms — "3 months and 17 days away" reads far more naturally than "108 days away" for most everyday purposes, even though they describe the exact same span.
The takeaway
Seeing two different-looking numbers from two calculators for what feels like the same question isn't a sign that one of them is wrong — check whether they're actually answering the same question (a total count) or two related but different questions (a total count versus a structured breakdown of that count).