Hi Dear,

CAT stands for Common admission test and is conducted at national level every year by Indian institute of management for admission into top b schools of India.

PET stands for Preliminary Eligibility Test and is conducted by Uttar Pradesh Subordinate Services Selection Commission (UPSSSC)  for the recruitment of Group C & Various Other posts.

TET stands for Teacher Eligibility Test  and is the common test conducted to recruit teachers in government-run schools across India.

CTET stands for Central Teacher Eligibility Test and is a national-level exam conducted by the Central Board of Secondary Education (CBSE) for getting teaching jobs in government schools from Class I to Class VIII.

Hope this helps.. Good Luck