That's a difficult question -- information lifecycle management (ILM) and hierarchal storage management (HSM) mean many things to many people. Some users view ILM as little more than tiered storage, while others see ILM as more of a logical/management feature. Generally speaking, ILM involves moving or migrating data while leaving behind a pointer to the actual data location. Differences include the way that ILM and HSM initiatives are implemented and the impact on applications while data is being moved. This approach is more appropriate when data remains active, but it's importance is matched to the performance of a particular storage tier.
On the other hand, file archiving involves moving the entire file discretely to a totally new location and removing all traces of the file from its previous location. Archiving is for long-term preservation. It frees up storage space and directory entries for new and more important data. There are some hybrid solutions that combine archiving and tiering.
Go back to the beginning of the File Archiving FAQ Guide.