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QoS features first depend much whether supported by hardware, e.g. typical Catalyst switch, or by software, a software based router (e.g. an ISR).
The platforms supporting QoS via hardware generally don't change QoS features between IOS versions. As platform hardware architecture is often different, QoS feature support is different too. Incidentally, on chassis platforms, QoS features can vary based on supervisors and/or line cards.
The platforms supporting QoS via software are more likly to change between IOS versions. Feature release notes might be compared, along with the IOS reference and guide manuals, for what's been changed. Generally, software based platform QoS features are usually identical (or almost) for the same IOS version on different platforms.
Unfortunately, all of the above sort of precludes an easy way of knowing all the QoS feature differences between platforms or IOS versions. Further compounding this problem; there's no "standard" QoS feature set.
As I write this, I'm involved in a project to implement a consistent QoS model across all our switches and routers. We too have many different platforms and so we've defined a template for each platform or model series or platform/model family that the same (or similar) QoS commands might be used.
