First let's explain the difference. A really good article on Journaling is included below as well as the definition of the two:
Journaling with Exchange Server 2003
"Journaling is the ability to record all communications in an organization. E-mail communications are one of many different communication mechanisms that you may be required to journal. Therefore, journaling in Exchange has been developed to enable the messaging administrator to feed messaging data into a larger journaling solution, while using minimum overhead.
It is important to understand the difference between journaling and archiving. Journaling is the ability to record all communications; alternatively, archiving refers to reducing the strain of storing data by backing it up, removing it from its native environment, and storing it elsewhere. That said, you may use Exchange journaling as a tool in your e-mail retention or archival strategy."
For journaling, customers are using the journaling that is built into Exchange 2003. Some send all of this to third party solutions either on site or elsewhere for storage and they use other means to search and retrieve that data when it is needed.
For ideas as to what our partners can provide please as far as the archiving portion of this check out the following article:
Supporting Regulatory Compliance with Exchange Server 2003
Our partners in this space are IXOS, KVS, LEGATO Software, and ZANTAZ.