There is no differentiation. "Largely discussed in this thread" and "Discussed largely in this thread" have the exact same meaning.

Edit: The only difference is the intonation as you say the words in the different sentences.

"Largely discussed in this thread" has a downward slope.

"Discussed Largely in this thread" goes up to Largely, and then downwards after.

Edit 2: Even then, it may be less intonation, than emphasis.