Observer vs. Viewer

Observernoun

One who makes observations, monitors or takes notice

‘Most impartial observers agreed that Sampras had not served well.’;

Viewernoun

Someone who views a spectacle; an onlooker or spectator.

Observernoun

One who adheres or follows laws, guidelines, etc.

‘I shall be an observer of the local customs.’;

Viewernoun

Someone who watches television.

Observernoun

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

‘The UN sent many observers to the country's first elections.’;

Viewernoun

Any optical device used to view photographic slides.

Observernoun

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

‘The Vatican and Palestine have observer status at the UN.’;

Viewernoun

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

Observernoun

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

‘The only crew-member to survive the crash was the Canadian observer.’;

Viewernoun

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

Observernoun

(military) A sentry etc. manning an observation post

‘We waited till dusk when the observers' vision was poorest.’;

Viewernoun

One who views or examines.

Observernoun

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 observed of all observers.’; ‘Careful observers may foretell the hour,By sure prognostic, when to dread a shower.’;

Viewernoun

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

Observernoun

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

‘These . . . hearkened unto observers of times.’;

Viewernoun

The superintendent of a coal mine.

Observernoun

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

Viewernoun

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

‘the spectators applauded the performance’; ‘television viewers’; ‘sky watchers discovered a new star’;

Observernoun

A sycophantic follower.

Viewernoun

an optical device for viewing photographic transparencies

Observernoun

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

Observernoun

an expert who observes and comments on something