Observer vs. Viewer — What's the Difference?

One who observes

One that views, especially an onlooker or spectator.

One who is sent to observe and report on events or proceedings without directly participating in them.

Any of various optical devices used to facilitate the viewing of photographic transparencies by illuminating or magnifying them.

A crew member on a military aircraft who makes observations.

A person who watches television or movies

A member of an armed force who watches and reports from an observation post.

Someone who views a spectacle; an onlooker or spectator.

One who makes observations, monitors or takes notice

Someone who watches television.

One who adheres or follows laws, guidelines, etc.

Any optical device used to view photographic slides.

A person sent as a representative, to a meeting or other function to monitor but not to participate

(computing) A program that displays the contents of a file.

A country or other entity which has limited participation rights within an organization.

The manager of a colliery, who directs its workings and ventilation.

(military) A crew member on an aircraft who makes observations of enemy positions or aircraft

One who views or examines.

(military) A sentry etc. manning an observation post

A person appointed to inspect highways, fences, or the like, and to report upon the same.

One who observes, or pays attention to, anything; especially, one engaged in, or trained to habits of, close and exact observation; as, an astronomical observer.

The superintendent of a coal mine.

One who keeps any law, custom, regulation, rite, etc.; one who conforms to anything in practice.

A close observer; someone who looks at something (such as an exhibition of some kind);

One who fulfills or performs; as, an observer of his promises.

An optical device for viewing photographic transparencies

A sycophantic follower.

A person who becomes aware (of things or events) through the senses

An expert who observes and comments on something