With only the word “of” being the difference, Front End of Innovation and Front End Innovation actually have two different meanings.
The Front End of Innovation ‘Stage’ is also sometimes described as the “Fuzzy Front End”, “Phase 0”, “Stage 0” or “Pre-Project Activities”. It is the starting point where opportunities are identified and concepts are developed prior to entering the formal product development process. The Front End of Innovation is where exciting breakthroughs are created through a process that allows for creativity.
Koen distinguishes five different front-end elements (not in any particular order):
The Front End Innovation ‘Process,’ unlike the Front End OF Innovation, is not “Fuzzy.”
Unlike in formal development, Front End Innovation is not a standard linear process. Front End Innovation has five categorically distinct efforts which allows for discovery, creativity, and concept validation. During this process, new input results in analysis that triggers re-evaluation of prior assumptions – an outcome of discovery and inspiration.
Although the process is not sequential, all steps of the process must be completed until all assumptions are tested and modified. Participants in the process must be jointly satisfied they have reached an optimal result. The result of this iterative discussion is a well calculated innovation ready for the formal development process.
 Koen et al. (2007), Providing clarity and a common language to the ‘fuzzy front end’. Research Technology Management, 44 (2), pp.46-55