Throttling:
Throttling limits the speed of all services and protocols (i.e. the overall speed of your internet connection).
Regardless of the line speed, a throttled account will only be able to achieve limited speed when throttling is applied. The line itself is not affected, and using an unthrottled account will return line performance to normal.
Throttling is applied on an individual per user basis, based overall usage within a given month. Throttling is only ever applied when demand on the network exceeds available network capacity, and is de-activated when demand returns to normal levels.
Shaping:
Shaping is the implementation of protocol-based priority, to manage demand on the network (i.e. some parts of the internet are made to be faster than others, using prioritisation).
When shaping is implemented, realtime, interactive services are given higher priority than non‑realtime, non-interactive services, effectively slowing the performance of non-prioritised services in favour of those that are more important to an overall good broadband experience. Shaping can be applied to any user on a shaped data package in general (not based on usage thresholds), and the impact to non-priority services is determined by the level of demand and available network capacity.
Shaping is applied only when demand on the network exceeds available network capacity, and relieved when demand decreases.