Are there any differences (general or regional differences) between "in order to", "so that" and "so as to"?
I've seen that they may be interchangeable, but I'm not so sure.
Google Ngrams gives, for American English (red = so that, blue = in order to, orange = so as to):
and for British English:
Doesn't look like there is much of a difference between American and British English in that matter.
verb1 + to +
verb2 has simple, direct relationship (usually a purpose) with
I bought a coke to drink.
verb1 so as to
verb2 is a resulting action one hopes to get from verb1. Therefore,
verb2 may not directly related in common understanding.
I work hard in order to save money for a vacation this year.
In order to is a formal way of saying so as to.