Question

What did Nazi camp administrators do to identify people from different groups in the concentration camps?

Answer 1

They used different colours of emblems.

Explanation:

The most well known is the yellow Star of David worn by the Jews. However there were emblems of different colours for Jehovah's witnesses, Freemasons, and homosexuals amongst others.

Answer 2

Also Numbers
Each Camp had a punch card machine to handle database queries.
Longer term prisoners were kept for their skills and the punch card system helped effectively use them.

Explanation:

https://en.wikipedia.org/wiki/IBM_and_the_Holocaust

The book brings to light many controversial aspects of the use of Punch Card Technology during the War. Its accusations against IBM have not been resolved.