Differences between "coordinate" (n.) and "co-ordinate" (n.)

I can't seem to spot any differences or usages where one would use the hyphenation version versus the non.

According to Online Etymology they both point to coordinate.

I can see co-ordinate (v.) being used like co-pilot or co-chief, meaning a daulity or partner version. Example: Would you please co-ordinate with Bob. Meaning Bob is already ordinating and if you would also ordinate with him.

Yet I don't see that transferring over to the noun version meaning a location, especially in reference to mathematics and geography.

Is it simply a mix-up, or perhaps a localization issue (UK uses -, USA doesn't) or am I completely off base here?

Making a quick search in my NOAD, it seems they are the same exact term.

But, like I was thinking, coordinate is the term used, since if you search for co-ordinate, it will redirect you to the other one.

Look what happens if you search for co-ordinate in the OALD.

If you type them in Google, you'll get the following results:

• Co-ordinate: About 5,190,000 results;
• Coordinate: About 58,100,000 results.

Quite a difference... In the end I suppose the hyphened version is a variant, you might use either, although nowadays they're not really considered compound words anymore (another similar words is cooperate) but single words.

Is it simply a mix-up, or perhaps a localization issue (UK uses -, USA doesn't) or am I completely off base here?

Yes, it is a local issue. I know from my experiences, that co-ordinate is the more common spelling in the UK. It's commonly used and is the spelling that I was taught, in the UK.

Whenever I have seen the word used in American writing, in publications or on the internet, I have noticed that it has always been with the coordinate spelling.

These dictionary pages mention that co-ordinate is the spelling in the UK.

http://dictionary.cambridge.org/dictionary/british/coordinate_1?q=co-ordinate#coordinate_1__3

http://www.ldoceonline.com/dictionary/coordinate_1

http://www.ldoceonline.com/dictionary/coordinate_2

http://www.ldoceonline.com/dictionary/coordinate_3

According to Longman DOCE, co-ordinate is British English.

And for better understanding of hyphen usage see Oxford Dictionary:

Usage
In modern English the use of hyphens is in general decreasing, especially in compound nouns: website is preferred to web-site, and air raid to air-raid. Hyphens are still often employed where a compound expression precedes a noun, as in first-rate musician or twenty-odd people (twenty odd people means something quite different!), but even in this context there is a growing trend to omit them. When a phrasal verb such as build up is made into a noun it is usually hyphenated (a build-up of pressure ). Note, however, that a normal phrasal verb should not be hyphenated: write food to take away not food to take-away, and continue to build up your pension not continue to build-up your pension

They are the exact same term, as Alenanno says. The reason for hyphenation is likely due to the fact that 'oo' has a different pronunciation than desired. In my experience with American English it's a preferred spelling when the word used is not likely to be familiar or when the pronunciation would otherwise be easily misread.

'Cooperate' is sometimes seen as 'co-operate' just to highlight that the double 'o' is two different vowel sounds. 'Cooperate' could be pronounced like 'coop' (as in a chicken coop). Words like 'co-opt' are still always spelled with a hyphen precisely because of this.

'Cooperate', 'coordinate' and other words are common enough that the word is accepted sans-hypen. People now recognize these words so the hyphen has stopped being necessary.