The VXR has a faster backplane than it non-VXR equivalent ie, VXR can go up to 1Gbps as opposed to 500Kbps for non VXR.
Also the VXR has intergrated multi-service interchange functionality. From cisco doc
Integrated Data, Voice, and Video (Multiservice) Solutions
The integrated multiservice interchange (MIX) bus on the Cisco 7200 VXR chassis delivers flexible support for hybrid environments including time-division multiplexing (TDM) voice, voice over IP (VoIP), and voice over Frame Relay (VoFR). Digital voice port adapters provide large-scale, high-capacity voice termination to private branch exchanges (PBXs) and the public switched telephone network (PSTN). With high-density Digital Signal Processors (DSPs) and T1/E1 interfaces, these modules have the horsepower to deliver up to 60 channels of highly compressed voice for bandwidth-sensitive WAN applications and up to 120 channels of toll-quality voice for large LAN and campus voice applications.
Indeed it has to do with voice capabilities, as previous poster have mentioned, the presence of the MIX bus allows voice cards to share DSP resources of PA-VXA card with PA-MCX cards. Another application is drop and inster TDM mux.
We are pleased to announce availability of Beta software for 16.6.3.
16.6.3 will be the second rebuild on the 16.6 release train targeted
towards Catalyst 9500/9400/9300/3850/3650 switching platforms. We are
looking for early feedback from customers befor...
Introduction Featured Speakers Luis Espejel is the Telecommunications
Manager of IENova, an Oil & Gas company. Currently he works with Cisco
IOS® and Cisco IOS XE platforms, and NX to some extent. He has also
worked as a Senior Engineer with the Routing P...
In this session you can learn more about Layer 3 multicast and the best
practices to identify possible threats and take security measures. It
provides an overview of basic multicast, the best security practices for
use of this technology, and recommendati...