Two changes that I can see are:
Rule 4(j) the airline Gestair has been dropped from the list of IB-affiliated airlines that can be used
Rule 5 the rule on voluntary downgrades to lower cabins has been slightly improved
Old Wording was:
NOTE: For flights where First or Business Class is not offered or available, passengers may travel in a lower Class, in the applicable booking code for that lower Class.
The new wording is:
NOTE: For flights where First or Business Class is not offered or available, passengers may travel in a lower Class, in the applicable booking code for that lower Class.
Where the applicable booking class for the lower class is not available,
Passengers travelling on First Class Fares may book Y class
Passengers travelling on DONE* Business Class Fares may book B class