what's the difference in camera on Galaxy S5 and iphone 5?

Both phones have great cameras, but I'd give the edge to the iPhone's. The GS5's takes higher-resolution photos, but even when zooming or cropping, I think the iPhone's shots look better. Generally speaking, the GS5's shots look very saturated, while the iPhone's capture more subtle nuances of color in all lighting conditions.

The Galaxy's camera is also annoyingly slow to fire up from the lock screen: on it I can go from locked screen to snapped pic in about 6 seconds, while on the iPhone it takes about 3 seconds.

The iPhone has a slow-motion recording mode that's terrific (it records in 720p at 240 fps). If you have pets or go to lots of sporting events, it's especially nice to have. The GS5 has a slow-mo mode too, but it looks grainy and choppy compared to the iPhone's. You also can't adjust which segments of the GS5's video are in slow-mo and which are in regular speed, like you can in Apple's version.

The iPhone also has the advantage in low-lit shots. I snapped some test pictures in a dark (and messy) closet, with the flash off. As you can see, the difference was, quite literally, like night and day:

A dark closet, taken with the iPhone 6 (Photo: Will Shanklin/Gizmag.com)
The same dark closet, taken at the same time, only with the Galaxy S5 (Photo: Will Shankli...
It's not that the Galaxy S5 has a bad camera. On the contrary, I'd say it's one of the five best smartphone cameras I've used. But, in my experience, the iPhone's is simply better.

Different cameras have different specs, and different settings (even though both cameras might be set to default). Not only the mega pixels count, also the quality of the real sensor that captures the picture. After that, comes some post processing (with Samsung usually choosing to sharpen the picture).
In your case, the settings at that moment made one picture look better than the other. If both of you clicked the HDR option, the outcome may have been switched (though I suspect only slightly, if at all).
Therefore, always check your picture after shooting it for the best results (so you can quickly ake adjustments and re-shoot).

My iphone photos are consistently washed out and poor color quality, especially indoors.  What settings can I adjust on the camera to make them better?