I wonder whether the initial question would'nt be rather about the difference between the C414B-XLS and the newest C414 XLS.
Originally Posted by AKG web site
The new models C 414 XLS and C 414 XL II offer nine pickup patterns which enable to choose the perfect setting for every application. For live-sound applications and permanent installations all controls can be disabled easily for trouble-free use. A Peak Hold LED displays even shortest overload peaks.
The C 414 XLS maintains the sonic character of the legendary C 414 B-ULS, the longest-lived C 414 model. Engineered for highest linearity and neutral sound, it is the most universal and versatile large diaphragm microphone for decades. Widely used for accurate, beautifully detailed pickup of any acoustic instrument the new C 414 XLS combines proven reference quality, leading-edge technology and state-of-the-art components.
Did someone compare these new mics to their 'B' counterparts C414 B
-XLS and C414 B