Both result-adjuncts and purpose-adjuncts can be introduced by so that. How can we tell the difference?

Both result-adjuncts and purpose-adjuncts can be introduced by so that. How can we tell the difference?

Both result-adjuncts and purpose-adjuncts can be introduced by so that, which is the main source of their confusion. However, in spite of this formal identity, there are some important differences that may help to keep them apart: a result-adjunct after so that is often, though not invariably, separated from the main clause by a comma while a purpose- adjunct is not; a purpose-adjunct after so that tends to contain a modal auxiliary while a result-adjunct usually does not; and a purpose-adjunct can stand in the initial position of a sentence while a result-adjunct normally keeps at the end.