I guess the title says it all. There seems to be no obvious difference between directory traversal and file inclusion vulnerabilities.
But I guess there must be some difference, since the www.cvedetails.com use the following categorizations:
Bypass a restriction or similar
Cross Site Scripting
Denial of service
Directory Traversal
Execute arbitrary code on vulnerable system
Gain Privileges
Http Response Splitting
Memory Corruption
Obtain information
Overflow vulnerability (includes stack and heap based overflows and other overflows)
Cross site request forgery(CSRF)
File Inclusion
Sql Injection
Among these we can notice both directory traversal and file inclusion, so they must be different somehow.