GSTIN & UIN

Unique Identification Number, UIN, is a special class of GST registration for foreign diplomatic missions and embassies which are not liable to taxes in the Indian territory. Any amount of tax (direct or indirect) collected from such bodies is refunded back to them

No both are different.
Format of GST UIN

GST UIN is a set of 15 digit alpha-numeric code which consists of 5 different sets.

First two digits refer to the State code;

Next ten digits refer to the Permanent Account Number (PAN);

Next digit refers to the Entity Number of the same PAN holder in a State;

The 14th digit is an Alphabet, i.e. “Z” by default;

The last digit i.e. 15th is a Checksum digit.

According to section 25(9) of CGST Act,2017 following are the persons to whom GST UIN should be granted;

Any specialized agency of the United Nations Organization.

Any institution or organization which are notified under the United Nations (Privileges and Immunities) Act,1947.

Embassy or Consulate of foreign countries.

Any other person notified by the commissioner.