What's the difference between heliograph and heliography?

Heliograph

Definition:

• (n.) A picture taken by heliography; a photograph.
• (n.) An instrument for taking photographs of the sun.
• (n.) An apparatus for telegraphing by means of the sun's rays. See Heliotrope, 3.

Example Sentences:

Heliography

Definition:

• (n.) Photography.

Example Sentences: