Hello,

If you are asking this question regarding TNPSC Group Exams.

Then it conducts exam for recruitment process at various levels.

There are four groups in this- 

Group 1

Group 2

Group 3

Group 4

The selection process differs here, let me explain in brief-

For lower level posts, there's only written examination,

For middle level posts, there's written one along with oral test,

Now, coming to the higher levels, there's preliminary, mains written and finally, oral test.This one is similar to UPSC process.

For more detailed information regarding TNPSC exam, its Groups, the positions included in each of them with eligibilit and exam process, kindly go through the notification by TNPSC I've attached below(it will clear all your queries)-

http://www.tnpsc.gov.in/recruitment-faq.pdf