The bulk update request #8703 has been rejected.
create alias film_grain -> noise
as far as i can see both these tags are used the same way.
film_grain would be reserved for the specific pattern of grain from analogue film ( e.g. https://i.imgur.com/b754LZh.jpg ) rather than a uniform texture, but i can't find any examples like this.
if the alias gets approved i'll sort out the two wiki pages as well