First rule of on-line bike ride tracking... every single one has secret-sauce that they use to tweak your ride data.
Strava ignores height information and simply plots your path's point locations on top of a map and that's how high you were. This method is pretty flawed if your GPS has placed you 20 metres off the road and you're in a deep cutting or on the side of a mountain with a hundred metre vertical drop to that side.
I don't know anything about the Cateye services.
The only answer is to take their results with a big pinch of salt, and merely work on improving the difference between the rides. Don't compare rides between different providers.