Difference in job roles in oracle

hi,

Kindly do provide specific differences and similarities between the following job roles. I do understand that google search helps, but I would like to hear from people who are in the following fields as to what exactly are the differences and similarities. Also do provide information on what are the common technologies or applns needed to be in touch with respect to the below roles.

1. Oracle Apps DBA
2. Oracle Apps Technical
3. Oracle Designer
4. Oracle DBA developer.

Thanks