Was hoping someone could give me their opinion on this.
Which of these two would you use, and is there a grammatical difference as to why you chose one over the other, or is it a british / american english usuage difference?
She lived in a modest furnished aparment.
She lived in a modestly furnished apartment.
Any advice is appreciated.
She lived in a modest furnished apartment. -- The apartment and all its appurtences are modest. Both adjectives modify apartment.
She lived in a modestly furnished apartment. -- only the furnishings are modest. The adverb modestly modifies the adjective furnished.