The Core Difference
Exclusive counting calculates the elapsed distance between points in time, analogous to measuring the distance between two mile markers. Inclusive counting treats the dates as discrete entities that are both part of the active period.
Hotel Stays vs Rental Periods
Hotel reservations are calculated exclusively: checking in on Friday and checking out on Sunday represents 2 nights of accommodation. Conversely, event passes and car rentals often calculate inclusively: Friday, Saturday, and Sunday constitute 3 full days of rental use.
How to Avoid Ambiguity
When writing contracts or agreements, specify "inclusive" or "exclusive" explicitly, or define the exact time boundaries (e.g., "commencing 12:01 AM on September 1 and terminating 11:59 PM on September 30").