First, how they are the same (numbers correspond to sources at bottom):

• Based on their search habits alone, B2B consumers are certainly behaving similar to B2C consumers. 83% of business consumers reported “always” beginning their purchasing process through Google search. This was followed by 26% who reported they always went to the technology vendor’s Web site.  “Discussion forums, online communities, or social networks sites,” came in second with 23% of respondents indicating that these were “very important” sources in influencing their purchase decisions, above other corporate assets such as Webinars (18%) and email newsletters (16%).1
• Intrusive marketing effectiveness is diminishing. The goal of marketing is to be found when consumers are looking, not intrude when they aren’t.1
• Traditional mass marketing with a B2B audience, like in B2C, “absolutely doesn’t pay off.”1
• B2B marketing will be catching up to the sophistication of B2C marketing with the following developments: Marketing automation software that accounts for the multiple influencers and decision makers; Multi-channel interactions; Market resource management, which incorporates the planning, budgeting, and marketing allocation (e.g., how much goes to PPC vs. print; campaigns vs. seminars); and Real-time data mining to enable personalized offers.1
• Many of the same social media principles we preach for B2C companies also apply to B2B.2
• Both B2C and B2B companies can leverage traditional media to support social media marketing activities.3
• Both B2C and B2B companies can be more interesting when they focus away from the product [or service] and toward how customers use it. On the social web it is how the product [or service] makes customers great that it is the defining success factor.3

And now, the differences:

• B2B customer relationships are often fewer and stronger than B2C relationships. B2C companies can have purely digital relationships with their customers and often have to as a result of the pure volume of customers. B2B companies use social media tools as a complement and not a replacement for face-to-face interactions.2
• B2C customers often aren’t competitors, however, the clients of B2B companies are often in competition with each other. Two local ice creams shops may buy their plastic spoons from the same supplier.2
• True, the B2B buyer has emotions just like the average consumer. However, she is still an employee of her company and must take into account her company’s needs when making a decision. B2B sales prospects have two sets of buying needs that don’t always dovetail with one another. You must address both if you are to maximize your chances to sell big-ticket B2B products and services. 4
• B2B, unlike B2C, can result in your product or service being perceived as an integral part of the customer’s business process, i.e. when “you” and “they” become “us.” When the relationship supports a mutually beneficial long term competitive advantage in the form of accelerated growth rates, operating economies and increased market share. Here, the client relationship emerges as a strategic partnership, an actual alliance. This is a far cry from the predictable transactional steps of a commodity sales process.5
• B2B buyers use heuristics in their decision making. Heuristics guide which options and information get considered and which get rejected, and they help us simplify complex decisions to their relevant core. All this is good, in fact, essential. It’s just not rational. The B2B world has the added complexity of not just one irrational decision maker, but many.6
• B2B buying decisions are usually driven by one emotion: fear. As a result, B2B buying is all about minimizing fear by minimizing risk. There is organizational risk, which can often be dealt with rationally, and personal risk, which is usually unstated and hidden from the rational process. Yet personal risk is a huge factor in B2B buying.6

Lastly, where B2C gets it right and B2B tends not to, is how it addresses its marketing. B2C companies live in a world where marketing is a strategic decision and marketers are involved in strategic processes.

“However, these are areas where many B2B marketers are traditionally weak: market-back product-development process, brand and reputation management, market-driven pricing. The implications for B2B marketers are straightforward: successfully managing these three core capabilities will increase the effectiveness of the marketing team and grow business overall.”7

In conclusion, in many ways B2B2C is a reality and there are many things that we can learn from each other, but in the end there are fundamental differences that remain.

1destinationCRM:  What B2B Marketers Can Learn from B2C

2Search Engine Watch: Social Media for B2B

3Social Media B2B: B2B Lessons From B2C Social Media Marketing Strategies

4B2B Sales & Marketing: Writing Emotional B2B Sales Copy

5B2B Sales & Marketing: Eight Key Steps to Building B2B Major Account Client Alliances

6Marketo: Beyond the B2B Buying Funnel: Exciting New Research about How Companies Make Complex Purchases

7MediaPost:  Study: B2B Needs to Learn From B2C