In the US “sleet” is the term for a winter precipitation that occurs when snow falls through a layer of warm air and melts into water droplets, then re-freezes into ice pellets as it passes through colder air closer to the ground. In many other areas that were part of the British empire that precipitation is called “ice pellets” and “sleet” instead refers to a mix of snow and rain. In the US that’s called a “wintry mix.”
I had to go looking to see if there was a distinction. There is!
Hail is a form of solid precipitation.[1] It is distinct from ice pellets (American English “sleet”), though the two are often confused.[2] It consists of balls or irregular lumps of ice, each of which is called a hailstone.[3] Ice pellets generally fall in cold weather, while hail growth is greatly inhibited during low surface temperatures.
Unlike other forms of water ice precipitation, such as graupel (which is made of rime ice), ice pellets (which are smaller and translucent), and snow (which consists of tiny, delicately crystalline flakes or needles), hailstones usually measure between 5 mm (0.2 in) and 15 cm (6 in) in diameter.[1] The METAR reporting code for hail 5 mm (0.20 in) or greater is GR, while smaller hailstones and graupel are coded GS.
https://en.wikipedia.org/wiki/Hail