I was intrigued by this query because of other niggling (for me, at least) -er/-or distinctions. Here, I'm talking just about the use of these letter combinations as agentive suffixes--i.e. endings that turn verbs into nouns meaning 'someone who VERBS'. Of course, there are other -er and -or endings that differ in AmE and BrE (centre/center, color/colour), and those are what you find if you try to look up AmE versus BrE differences in spelling -er and -or words. But that's an unrelated issue that we'll just ignore for now.
So, both -er and -or are agentive suffixes. The -or suffix is
Things are less clear-cut with other Latin-derived verbs. For example, in my job, I advise students and convene courses, and when I spell out those roles, I'm an advisor and a convenor, but when my UK university spells them, I'm often an adviser (which just looks wrong to me) and a convener. (Incidentally, Blogger's allegedly AmE spellchecker likes the -er forms.)
So, is this a dialectal difference, or just personal perceptions? (It's not a pronunciation difference, except in those cases in which one exaggerates the pronunciation in order to give a clue to the spelling.) I've searched for advisor and adviser on a range of university websites from the UK and the US, and here's what I found:
US Universities adviser advisor U of Massachusetts (Amherst) 10% 90% U of Illinois (Urbana-Champaign) 27% 73% Baylor University 31% 69% UK Universities U of Sussex 38% 62% U of Manchester 36% 64% U of Edinburgh 49% 51%
So, it's probably not my imagination that the -or form is stronger in the US than the UK, though there's considerable variation within each country. The fact that I started out at the university with the strongest preference for -or might account for my strong preference for it. There's also the question here of whether this distinction can be attributed to regional differences within the countries. We see the strongest -or preference in the US in a northeastern university. Did I get that strong preference because of my university experiences, or had it already been inculcated in me by growing up and learning to spell in the northeast? In the UK, we see the weakest -or preference in a Scottish university. Does that extend to other Scottish universities? I'm not going to spend my Saturday finding out! But you're welcome to!
Before we leave this topic, let's raise the question of whether these spelling differences are meaningful. There's a general principle at work in language (sometimes called the Principle of Contrast) that if there are two different forms, they must have some different significance. This is why it is difficult to find exact synonyms in a language--once you introduce a new word for something, people start to assume that it must give some different information from that given by the old word for that thing (otherwise, why bother to coin or borrow the new word?). The Principle of Contrast (and avoidance of synonymy) is so strong that it can be extended to spelling variations. So, for example, I was once party to an American discussion of grey versus gray (the latter being the more common AmE spelling, but the former being acceptable as well), with people discussing whether grey or gray was a darker colo(u)r. (The discussion began here; search the American Dialect Society archives for 'grey and gray' to get the whole string). Because there are different forms, and because people like to look for differences in meaning and maybe because they have been exposed to one form more in one type of context than another (e.g. grey in clothing catalog(ue)s, but gray in a box of crayons), people often believe that the words have different definitions. This discussion has happened (for about 100 years!) at the OED, too, where there's a note at the 1989 grey/gray entry that reads:
With regard to the question of usage, an inquiry by Dr. Murray in Nov. 1893 elicited a large number of replies, from which it appeared that in Great Britain the form grey is the more frequent in use, notwithstanding the authority of Johnson and later Eng. lexicographers, who have all given the preference to gray. In answer to questions as to their practice, the printers of The Times stated that they always used the form gray; Messrs. Spottiswoode and Messrs. Clowes always used grey; other eminent printing firms had no fixed rule. Many correspondents said that they used the two forms with a difference of meaning or application: the distinction most generally recognized being that grey denotes a more delicate or a lighter tint than gray. Others considered the difference to be that gray is a ‘warmer’ colour, or that it has a mixture of red or brown (cf. also the quot. under 1c below). In the twentieth century, grey has become the established spelling in the U.K., whilst gray is standard in the United States.So, do advisor and adviser mean different things to you? Or does one just seem misspelt?