Most of the times, in a B2C model we sell a product and in B2B model we sell a concept. Do you agree or disagree? Let me know your views.

Sure B2B and B2C is difference marketing modules, On the both of them we sell a product or service to a person.
But the purchasing motivation is different, And the needs also different when it comes to the information that they need in order to make the decision to purchase.

B2B and B2C are business models, not marketing models! and I am not really sure about what do you mean by "concept", you might mean "service" or "value", and both are way different than each other and than a concept ! Long story short, in both business models you may sell a product or service, and to do so; you need to create the demand by delivering the right value and create the right positioning.
Examples: B2C Business model company selling products to consumers: a company selling diapers, like Procter and Gamble B2B Business model company selling products to companies: a company selling ERP solutions, like Oracle B2B Business model company selling service to companies: a company selling security services, like Securitas B2B and B2C hybrid model a company selling cars "products" for both business and consumers like trucks and sedans like Chevrolet B2B and B2C hybrid model a company selling cleaning "service" for both house owners and companies And all of them has to have a clear value to deliver for the client whether are consumer or a business company, as well as a clear positioning in the client mind.

Agreeing to what Ghina and Tamer says I understand that marketing has much lesser role in B2B 'cos it's the salesmen who are the face of the company and relation with customers as they are the ones who visit a customer most frequently (hence the relation builder).
From what Tamer says a Rolls Royce won't need TV ads whereas a Honda vehicle will.
So whereas former is pure brand buying the latter is brand+benefits buying.
So one is B2B whereas other is B2C ?

In B2C you are selling concept as well, example: A 1975 Rolls Royce car has features less than a 2000 Honda Civic, a representative of Honda sells a product talking about features, on the other hand, The Rolls Royce representative sells a concept based on the mental value.

I have to say that I disagree.
At its core, B2B is a model that is relationship driven as it deals with two businesses, one selling, the other buying.
In this model, anything can be sold, be it a concept, an idea, a product, a business entity etc.
In B2C, you are correct, it is product driven as it is focused on getting the end product to the consumer directly.

This is a purely scientific terms Because all the products are in the end is a service, as well as all the services are a product

B2B is solutions markets , no CEO in the world will wake up at morning and says " today is a nice day i'll buy a drill !!! " drill solve a problem ,i need a hole on the wall so i buy a drill to achieve that , same logic as i think B2B customers only and always purchase a solutions for their business , solutions can be concepts , products services or even idea's

I have to disagree.

B2B sales from an engineering point of view involve sales of massive expensive equipments. From IT point of view it may be ERP. From R&D point of view yes it can be just technology and concepts. But in general B2B anything can be sold! :-)

disagree, in both situations  we can sell product, service or concept

Business-to-business (B2B) and business-to-consumer (B2C) marketing is different The first step in developing marketing strategy for B2B is similar to the first step in a B2C strategy: identify who the customer is and why they need to hear your message, but B2C marketing campaigns are concerned with the transaction, are shorter in duration and need to capture the customer’s interest immediately.
Although the goal of B2B marketing is to convert prospects into customers, the process is longer and more involved.
A B2B company needs to focus on relationship building and communication using marketing activities that generate leads that can be nurtured during the sales cycle.