A metered-dose inhaler (MDI) is a device that delivers a specific amount of medication to the lungs, in the form of a short burst of aerosolized medicine administered by the patient via inhalation.
A dry-powder inhaler (DPI) is a device that delivers medication to the lungs in the form of a dry powder.
a nebulizer or nebuliser (see spelling differences) is a drug delivery device used to administer medication in the form of a mist inhaled into the lungs.
A Nasal spray works via actuation of a nasal spray bottle, used to deliver medication via the nostrils