The difference between Feast day and Holy day
When used as nouns, feast day means a religious festival for a particular saint or religious event, whereas holy day means a religious festival.
check bellow for the other definitions of Feast day and Holy day
-
Feast day as a noun (religion):
A religious festival for a particular saint or religious event.
Examples:
"17th March is St Patrick's feast day."
-
Holy day as a noun (religion):
a religious festival