Subject to where you are from, different countries have different terms for "storm drain".

Depending on where you are from, https://hoch-zillertal24.com/jonite-us-worlds-first-stone-reinforced-gratings/ have different terms for "storm drain".
Accordingly to Wikipedia, a storm drain is actually a tunnel that carry runoffs (rain) from urban areas. For a layman, it helps to think along the line of sewage system functions beneath our cities.
In america, this is typically referred to as "storm drain" or "storm sewer".
In the united kingdom, this is often called "surface water drain" or "surface water sewer".
In Australia and New Zealand, it is typically referred to as "stormwater drain".
And there you have it, next time you hear someone mentioning "storm drain", "storm sewer", "surface water drain","surface water sewer" and "stormwater drain", you now know they mean the same thing.
Functions of storm drain include draining excess water (rain or storm water) and ground water from pavement, streets and carparks into rivers and streams to prevent flooding.
Although storm drains do a amazing job of draining excess water from the urban areas, the inlets are essentially openings where left uncovered could be a danger to pedestrians. Left uncovered, rubbish will enter the storm drains and cause choking which may eventually end up with flooding.
To guarantee storm drains serve their purposes while minimizing the dangers posed to pedestrians and to prevent choking of the drains, drain covers (gratings) are used to cover the inlets (openings) of the storm drains to accomplish the two purposes.
At Jonite, we specialise in steel reinforced drain covers (gratings) which cover your storm drains while preserving the aesthetic components of the architecture around the drain covers.