Advanced Gold Exam maximiser with audio set and key, 10th ed./2006, new for 18 CHF; Advanced Gold coursebook, 9th ed./2006, almost new with few notes in book for 20 CHF; New proficiency Gold maximiser with key, 8th ed./2006, new for 12 CHF; New proficiency Gold coursebook, 8th ed./2006, fairly new with few notes in book for 12 CHF; Advanced Language practice with key, 2003 edition, new for 40 CHF; Advanced Grammar in use with CD Rom and answers, 2nd ed., new for 22 CHF. Ready to be picked up but I am also happy to send by mail (free of charge).

Hi, I'd be interested in the proficiency books, what's the difference between the 2 ? Cheers