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.”
As someone from the U.S. I have never heard of “wintry mix”. I currently live on the west coast, but I always grew up that wet mix of snow/rain/water on the ground as “slush”. Each country has its own regional dialects
Sleet has always been the slushy stuff near me. Hail is the hard frozen ice pellets that can crack a windshield. I don’t know what OP is talking about.