Mozzarella is unquestionably Italy's most popular cheese, smooth on the outside and soft on the inside. It has a millennium-long tradition in the Campania region, and it, like burrata, is loved all over the world. So let's have a look at the distinctions between them.
Both cheeses are prepared from fresh cow's milk using the pasta filata (stretched curd) process. While mozzarella, also known as fior di latte, has been produced in Campania since the 12th century, Lorenzo Bianchino invented burrata in 1956 in Andria, Puglia. Due to the difficulty of transporting dairy products due to severe snowfall, the cheesemaker opted to use stretched mozzarella curd as a casing to keep the cream. As a result, burrata was created.
Mozzarella is produced from curd, which you get by adding lactic ferments and rennet to pasteurized cow’s milk. Cutting the curd and removing the whey are the following stages. The curd is then chopped into strips and kneaded in boiling water, either manually or automatically, to make it "spin" or "stretch," resulting in mozzarella bits. The final step is to immerse the pieces in water to chill them down.
Burrata is created from the stretched curd of mozzarella, but it isn't the main ingredient; instead, it serves as a casing for the dairy product. A smooth and creamy filling is found inside: stracciatella, frayed pasta filata blended with cream.
Source:
https://www.lacucinaitaliana.com/italian-food/italian-dishes/difference-italian-mozzarella-and-burrata