Is there a subtle or significant difference in meaning between the following?
fill something in
fill something out
In my humble opinion, the two expressions are interchangeable and both mean to complete something, usually it's a form or an official document by filling in the blank spaces or filling it out i.e. become full.
However, is it true in some American English dialects, fill in means to supply information whilst fill something out means to complete something in its entirety?
This piece of information was imparted to me by a very competent American English speaker.
I am referring to an aspectual difference when out is used in conjunction with the verb.
I disagreed, based on instinct (common sense?), I sustain that there is no difference in meaning between the two. Oxford Living Dictionaries doesn't mention this subtle difference in meaning but I'm not an American English native speaker, maybe the user is onto something?