hydrography vs oceanography

hydrography and oceanography both are nouns.

Word	Noun	Adjective	Verb	Adverb
hydrography	Yes	No	No	No
oceanography	Yes	No	No	No

As nouns, oceanography is a hypernym of hydrography; that is, oceanography is a word with a broader meaning than hydrography:

hydrography: the science of the measurement and description and mapping of the surface waters of the earth with special reference to navigation
oceanography: the branch of science dealing with physical and biological aspects of the oceans

Other hypernyms of hydrography include oceanology.

hydrography (noun)	oceanography (noun)
the science of the measurement and description and mapping of the surface waters of the earth with special reference to navigation	the branch of science dealing with physical and biological aspects of the oceans