Gravitational waves are related to spacetime and notions in General Relativity.
https://en.wikipedia.org/wiki/Gravitational_wave Capillary waves are surface waves on a liquid such as water which can be influenced by the Earth's gravity and are known as gravity-capillary waves:
The confusion comes in because popsci writers sometimes use the term gravity waves to describe the recent LIGO results. Gravity waves has nothing to do with General Relativity's gravitational waves.
https://en.wikipedia.org/wiki/Gravity_wave
Bottom line is gravitational waves and gravity waves are separate physical phenomena caused by different physical mechanisms with unfortunately similar names.