What's the difference between oceanography and marine geology?
Oceanography is a broad discipline that includes biology, chemistry and physical studies of the ocean.
Marine Geology is a branch of Oceanography. Marine Geology is the study of the geology of the ocean floor including plate tectonics and paleoceanography.
Oceanography covers the watery bits; marine geology covers the rocky bits.
No Greg is right, oceanography includes marine geology:
Marine geology is the study of sediment cores, mainly in the Ocean Drilling Program. to measure numerous proxies and try to make sense of it. See also this.
In my very personal opinion, accumulated over the years, it's the most misunderstood part of Earth science.
Edit: That's challengeable of course.
This is a pretty reasonable summary...depends of course on what a particular department or group wants to be called.
Separate names with a comma.