Sweet Sue, Margaret, and Maggie dresses fit the hard plastic dolls from the 1950s that have a more slender body shape.
These include not only Sweet Sue, Margaret, Maggie, Binnie, Winnie, (by Madame Alexander), but Arranbee Dolls and others of the same body style. The 14″ size fits the Robert Tonner 14″ Betsy McCall as well
The SweetSue types will also fit the composition dolls of the same size, such as Deanna Durbin and Wendy Ann, as long as they are the same height.
For example, the 20″ SweetSue dress will fit the 20″ Deanna Durbin or the 20″ Nancy Lee. You will see that some of them also fit dolls in other categories, like the Robert Tonner 14″ Betsy McCall dolls, now out of production but still popular.