One of the obvious differences in failure modes between fixed and rotary wing is predicated on the fact that the lifting surfaces on a helicopter are spinning at around 400 rpm and are connected to the airframe via a very complex system of hinges, pivots, drive shafts, dampers, bearings and tie-bars. Not only is this engineering triumph spinning at 400 rpm, but it is (hopefully) finely balanced and tracked to provide a smooth ride. On a fixed wing, the lifting surfaces are fixed with bolts, fasteners, spars and welding and are an integral part of the airframe, attached in a far more sedate and civilized manner.
"So what" you ask?
Back to failure modes. You can do some serious damage to a wing assembly and still stay safely in the air. There are plenty of examples in history of losing quite important bits from a wing, and in the case of an Israeli F-15, almost the entire wing, only to land relatively safely and have a great story to tell in the bar. Not so with a helicopter. If you are unfortunate enough to either lose a piece of the spinny bits on top, or have something cause an major imbalance, the natural desire of the helicopter is to try and shake itself to pieces, shedding all the important bits along the way. It doesn't need to be the whole blade (which is instantly catastrophic), the loss of a tip cap, trim tab or chunk of filler will all cause your work/life balance to deteriorate rapidly.
Luckily these are rare events, but in terms of suffering damage to a rotating assembly, it will by its very nature lead to unstable and amplifying events. When things go wrong, they go wrong suddenly and violently.