There was a Celtic holiday Samhain on November 1, which began at sundown October 31. Much of Halloween traditions derive from Samhain. It is also possible that All Saints Day and November 2 All Souls Day were placed on the Celtic holiday.
All Saints Day and All Souls Day are more celebrated in Catholic countries and England. In Spain and Portugal, All Saints Day is a national holiday.
The only real difference between the thoughts I think is naming at the UK of Hallow’s Eve. I’m not sure if the other countries had a name or used the one from the Islands. According to the info I could find Hallow’s Eve means “holy” or “sacred” and signified the end of the harvest season and the beginning of winter.
wy69