I use the two interchangeably.
What Bo said. It's grey just about everywhere in the English-speaking world except the US. I remember getting really confused by the name Graymon in the Digimon series as a kid and it took me until I was twelve to figure out that it was just the US spelling of the word.
America is the hipster nation. "Metric system? Too mainstream" :P. It seems like every time there's a system in the english-speaking world, America finds it a good idea to do the opposite.
Yeah, I've always imagined it would be so irritating to do science in the US and having to learn a whole new measurement system for distance and temperature.
Some of the spelling is a little confusing too. Like everywhere else, metre is a unit of measuring distance and meter is a device used to measure something. In the US, both are spelled meter (as far as I'm aware).
I didn't know metre was a word, so I'm assuming they are both spelled the same. Meter is both used for distance (mainly Kilometer since it's so easily converted with miles) and for how long something is. The spelling isn't really a problem for me since it's normally pretty easy to figure out what others are saying (like gray and grey or color and colour), but learning the metric system every year is a bitch :P. I wasn't even taught the conversion factor (simply adding or subtracting a 0 every level) untill this year in chemistry.
Yeah, the word Kilometre looks extremely weird to me, we call it Kilometer. Like I said, the Hipster nation...
Actually read the threads you're commenting on.
Gray is the only way.
Looks better that way :)
I'm Canadian and I use gray lol.