The general differentiation between those RIPs are the way they handle the data!
EFI:
RIP - Process - Print
The Fiery RIP holds the PS or the PDF printfile!
CREO:
RIP - Process - store the data in an internal fileformat RTP (ready to print) - Print
The CREO RIP is primarly working with the RTP filetype
That means more better (KODAK/CREO Marketing) flexibility with rasterimages after the RIP process
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Colormanagement, both claim they are the best - anyway, EFI is using the latest ICC correction standars. KODAK/CREO is enabled to work with ICC profiles, but has no tool to make last edits on this ICC / Color correction for realy last changes before print. But this is workflwo philosophy, at wich stage in a workflow colors have to be corrected - EFI is on this more flexible.
In general is the printing apporach on an KODAK / CREO controller more the way like press user are working with their CTP enviroment - clear defined workflow and lets roll the engines ;-)
EFI from its past (Copierbusiness) is more the understanding, everything can be changed in the latest moment before printing starts.
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VDP relevance for a RIP is not the application, a lot of posters that writes here are willing to present their SW solutions. Keep your eye on the VDP technology!
PPML - an open standard from PODI
VPS - the KODAK / CREO own standard (very fast very powerfull)
VIPP - the XEROX own standard (very powerfull in transactional applications)
optimized postscript - ADOBE standard (forget it)
The SW Solutions like XMpie, PS Mail, Lytrod, Planet Press, blablabla (100s available) are using those standards to manage the datacontent that are transferd to the rips!!
My personal impression was always that the KODAK / CREO RIP is more stable!
Rgds
Thomas