I hear xxxone and xxxbody, such as someone and somebody, have exactly the same meaning. But I've read that somebody is slightly less formal, so someone is often used in writing (http://dictionary.cambridge.org/grammar/british-grammar/someone-somebody-something-somewhere). I've also read that they sound a bit different (http://grammarist.com/usage/somebody-someone/).
By the way, my favourite grammar book much prefers xxxbody somehow, but I like xxxone much more because it is easier to write and pronounce.
Which do you like more, xxxone or xxxbody? Which do you often use?
As Spangola says, this is not a conscious decision which native speakers make. We say or write whichever one sounds or feels best in the sentence. There is no rule, nor any deliberate preference involved.
We say "special someone" and therefore "someone special" much more than "somebody special". ("special somebody" doesn't sound too good)
"<em>I've also read that they sound a bit different</em>" - You don't say? :D
I don't think you're going to get any useful answers from native speakers on this unless they've studied English grammar in depth. This just isn't a concious decision native speakers have to make.
Spangola, Su.Ki., and 马先生
Thank you for your comments! I'm glad to know all your opinions. 马先生's example seems to be one of such unconscious decisions. I know native speakers always do that, but it is extremely difficult for a non-native speaker to understand it. All I can do now is to try to use xxxbody as well.
