Air Outlets

Grille general term for for any open grating.

Register one that controls air flow

Louvre a grate that the open is slats that can or can not be move to direct air flow.

Then as the AP said we make art on the grill(culinary),document it in a register and store art at the Louvre.

These words can be applied to a lot of things. You need look up the definition to see how they apply. To get a better understanding on their use when applied to air openings.

"Louvre" ≠ "louver"; "grill" ≠ "grille"; the odd spellings all but demanded a tweaked answer.

Grille, in the Heating, Ventilating, and Air Conditioning field is an air outlet or inlet that does not have a damper to adjust the flow rate of air through it. Usually the damper is located in the duct upstream of the grille where it will produce less noise when it is adjusted to reduce the air flow. The noise is attenuated by the ductwork.

A register is the same as a grille, except it has a damper attached. The damper will make some noise when it is partially closed to adjust the air flow. These can be used where it would be difficult to access a duct-mounted damper.

An outside air intake louver typically is used in an exterior wall. An intake louver has angled blades that allow air to come through but not rain if the air velocity through the louver is below the manufacturer's recommended velocity for air entrainment - the water is drained so it does not enter the building. Some louver blades are fixed but some have adjustable blades that can be opened and closed similar to a damper, and some have insulated slats. For an outside wall you typically want a birdscreen. Usually the architect will want to come to agreement with the mechanical engineer on the type/color/material of the louvers to be used; and the structural engineer may want to say what wind load the louver and mounting structure should be able to withstand. For ventilation air consult the codes for distance required from sources of contaminated air/vents.

A wall mounted exhaust louver may be the same model as the intake louver, and typically the catalog data give values for intake pressure drop and exhaust pressure drop at different velocities. Same architectural/structural considerations apply - and you should try to located it so the exhausted air is not a nuisance.

Louvers can be installed in doors to allow air to come in and replace exhausted air from a room. Don't do that in a door in a fire rated wall however.

A few manufacturers of louvers and/or dampers: Ruskin. Construction Specialties. Hartzell.

A few manufacturers of grilles/registers: Titus. Krueger. Price.

There are many others. Google to find their websites - most have good catalog data on the web.