At least in the U.S. UHT and ultra-pasteurized are not the same:

Ultra-Pasteurized Milk Ultra-pasteurized milk undergoes a more intense heat treatment, where it is heated to 138°C (280°F) for 2 seconds. This process extends the milk’s shelf life to 30–90 days under refrigeration. Ultra-pasteurized milk is packaged in paper or plastic, with the package being treated with hydrogen peroxide (H₂O₂) to ensure sterility and preserve freshness.

Heat Treatment: 138°C (280°F) for 2 seconds

Shelf Life: 30–90 days

Storage: Requires refrigeration

UHT Milk UHT milk is heated to 138°C (280°F) or higher for at least 2 seconds, making it nearly sterile. This high heat treatment not only kills bacteria but also allows the milk to remain shelf-stable for up to 6+ months without refrigeration, until it is opened. UHT milk is packaged in a hermetically sealed container that is sterilized, ensuring the milk remains fresh and safe to consume.

Heat Treatment: 138°C (280°F) or higher for 2+ seconds

Shelf Life: 6+ months (unopened, no refrigeration needed)

Storage: Shelf-stable, no refrigeration required