Difference between Salesforce.com and Force.com

The biggest difference between Salesforce.com and Force.com lies in the concept  on which both are based.

Force.com is based on the concept of Platform as a Service or commonly known as PAAS where as Salesforce.com is based on the concept of Application as a Service.

So, we can say Salesforce.com is an application build by SFDC on force.com platform and has been made available to people for use at a per month per license pricing.

As a rule of thumb: Force.com platform license is three times cheaper then the Salesforce.com license but takes three times of effort and time to build any functionality which is billed in Salesforce.com application.

Force.com is the platform because of which SFDC says sky is the limit for developing any application. There are numerous examples of the same on Appexchange where people have Build Contract Management, HR
Systems, Social CRM etc.

To see a demo of Contract Management build on force.com Platform CLICK HERE