Both the Ascension of Jesus and Assumption of Mary are Holy Day’s of Obligation
The Ascension is moved to the nearest Sunday (possibly because Mass attendance was low), so no additional Mass is needed. However, the Assumption was deemed very important and is usually not moved to the nearest Sunday (typically only when it falls on a Saturday).
Why is this? Why is it more important to celebrate the Assumption than the Ascension? Shouldn’t it be the other way around?