Definition reminder: Canon means “official list”
Each church Sui Iuris (all 23) maintains it’s own canon of holy days, feasts, commemorations. A few have more than one (Ethiopian and Roman Churches).
Then, there is the separate issue of which calendar is used for observing the liturgical calendar - Julian, Revised Julian, or Gregorian. Which also is up to each Church Sui Iuris, and a few use more than one. And most everyone uses the Gregorian in day to day life, so it can appear that the choice of calendar results in different canons of holy days in one given Church Sui Iuris.
Most of the Byzantine Rite Churches Sui Iuris have very similar canons of feasts and holy days. Only a handful differ. The Ruthenian and Ukrainian are almost, but not quite, identical, for example. All the big ones line up across the Byzantine Churches. Which calendar varies more widely - for example, The Ukrainians allow the parish to pick.
With different rites, different canons of feasts are the baseline. Some are universal… Nativity, Theophany, Easter/Pascha, Ascension, Epiphany, Nativity of Mary, Assumption/Dormition.
Note also: the Roman Church has at least 4 different canons of feasts and holy days…
The Modern Roman Calendar - for the 1970 and later missals.
The Trent Calendar - as modified up through 1962 by Rome - for the Traditional Latin Missal.
The Dominican Calendar - the Dominicans have much overlap, but some dates differ, and a few are commemorations that are not on the general Roman calendars.
The Anglican Calendar - the list of feasts is noted in the front of the Anglican Use missal.
I believe, but am not positive, that the Mozarabic, Bragan, and Ambrosian uses also have their own canons of feasts.
The Ethiopians have parishes using the Ethiopian and Eritrean liturgies, and I recall reading that the canon of feasts is different between them. Also, many Ethiopian Church priests also celebrate the Roman Rite…