What is the difference between typical business valuation and IP valuation?

Mike Pellegrino, in BVR’s Guide to IP Valuation, distinguishes between a generic business valuation engagement and an IP valuation assignment. 

Business valuation engagements typically constitute consideration of the entire enterprise, including all historical and reasonably prospective value propositions. For example, a business owner wants to have a gas station appraised for estate planning purposes. It is straightforward to specify this job and come to a mutual understanding of the work effort.

IP is more difficult because IP represents a right that may comprise a unique set of restrictions. Restrictions may include a geographic restriction (a national border at the broadest level or a geographic region at a contractual level), a market restriction (perhaps through a trademark specification), or, a product restriction (perhaps through a patent specification), among others.