Apologies for the delay in responding ftdale...
There's the obvious simple answer to consultant value-difference. However if you are trying to market yourself in a pure search engine marketing (SEM) environment, it gets trickier to describe, so I will try and illustrate my reply with an analogy. However first things first?
The simplest notion of value-difference is much the same as unique selling point idea that sales people use; focussing on, highlighting and amplifying the benefits of a product or service in front of a potential client, whatever the medium. It is certain that if you are not clear about your uniqueness and the benefits you bring as a consultant, your professional life will not reach the dizzy heights you want it to.
As for your web presence - assuming you are relying in most part on it to get clients - there are many issues that you need to rein in and make work together. Paradoxically enough, this modern complex environment could perhaps best be described through the analogy of trying to win chariot race, as seen in the epic film Ben Hur. In this film the central character has a team of horses, and his selection and control of the horses is not too dissimilar to the processes that a consultant (or even companies in general) need to understand, master and use to their advantage. So, indulge my fertile imagination for a moment and I will try and explain?
Your first inner guiding horse is of the Keyword breed. It is nourished by the language of clients in your target sector, to an extent dictates your business pathway, and proffers the principle navigation routes through your site. Before setting out to put any resources into a race with Keywords, you have to establish whether there is a firm pathway actually exists. In other words if no potential clients are looking towards this arena, there is no prize money to be gained. So be sure of your keyword arena first and you may better understand where client challenges and motivations lie.
Design: Your second horse is named Forsite, of well-designed breeding. Focussed, and working alongside the navigated paths, it keeps an eye on your destination; on winning the prizes of your client arenas. Its constant 24/7 presence possesses a purposeful and strong identity to get you to the prize money (conversion). It may even have your brand stamped across it - it is always adorned with the portfolio of prior races won.
The third horse is the thoroughbred, a result of repeated optimisation. It will fine-tune and enable the performance of your first-two horses. Your knowledge and control of it, will draw to you the searching eye of the online race commentators (Google, Yahoo, MSN etc.). Where an optimisation really succeeds as a crowd-drawer, it is because it harnesses the strengths of Forsite and your last, outer horse named:
Market-Thing! This must always be the last of your four horses to attached. However, don't ever be fooled into believing you can win a modern consultancy race with only Market-Thing (no matter how clever it is!). One-horse races have merits but limited ones; the finish line and the pot of client prize money won't be easily obtained if there is a lack of conviction that they are paying for something that is not of a character that has really been tested.
You certainly have to have the stamina, strength, conviction and persistence to get online and established to win the online consultancy contest. Oh yes, and above all, a sense of humour.