Sleet, freezing rain. Sleet, freezing rain. Sleet, freezing rain. Some people, even weather men and women on the news, will use these two terms interchangeably, as though they're the same thing. And they're not too far off, truth be told - though the difference is dire enough that getting it right is rather important.
From a formative standpoint sleep and freezing rain are fairly similar. They're both forms of precipitation that show up during colder months of the year (or in cold weather countries and territories), the result of weather fronts bringing in frosty water vapor that turns into ice crystals. If the weather is cold enough the result of this is simply snow, though while the weather is still changing from warm to cold you're likely to get these two mixes.
Sleet is the closest intermediary stage to snow. It is almost like unformed snow, as sleet is little more than a combination of ice crystals and water droplets mashed together. The clouds in which the sleet existed before the saturation point weren't in a cold enough space to completely freeze the water before it fell, and so you get mushy sleet that's both snow and water. Wet packing snow is often the result of this combination, as well as ice patches as the water freezes when it hits the cold ground.
Freezing rain, on the other hand, is still a liquid. It is formed when a warm front comes in and buggers the cooler air containing the ice crystals, preventing it from staying frozen. This newly warmed water then plummets down to the Earth when it hits saturation and chills on the way down as it approaches the ground, which is just as cold as ever. When freezing rain hits it does exactly what its name suggests, freezing in thousands of small patches on the ground.
Sleet, in its way, can do this too. The accumulation of slushy snow, however, renders it slightly less potent as a threat than freezing rain: an Earth coated in ice becomes difficult to navigate for legs and wheels alike, and the sudden weight imposed upon fragile objects like telephone and power wires can result in rather catastrophic problems once the freezing rain lets up. Freezing rain is especially dangerous for airplanes, as it can freeze their wings and engines with relative ease.
Make no mistake, both sleet and freezing rain are dangerous if you don't pay attention to the aftermath of the storm. Knowing what's going to happen ahead of time is important for planning your days, however, and consequently knowing the difference can completely change how you treat one storm or the other.