Line Dancing
According to Line Dancing with Sharlo, line dancing consists of a group of people standing in rows of lines and performing the same dance steps simultaneously. The participants all stand facing one direction and move according to the music. Line dancing doesn't just consist of moving your feet, it can also include pivoting to turn directions, clapping hands and sliding, depending on the song you're dancing to. Although line dancing is done with a group of people, it's very much an individual dance in the sense that you don't need a dancing partner.
Square Dancing
Unlike line dancing, square dancing typically consists of a set number of people, eight, completing various different dances as they're assigned by someone known as the "caller." The eight dancers typically pair up to perform the dance assignments. There are two main types of square dancing: traditional square dancing, which is danced in alteration with contra dances; and modern western square dance, which is a more modernized take on the dance.
Music
Although line dancing can be performed to any song, there are certain titles that it's more popular with. These include songs like "The Hustle," "Cha-Cha Slide" and "Cupid Shuffle," which are popular at weddings. Line dancing is also associated with country western music and is often performed at country-themed bars. Square dancing, on the other hand, is best associated with country and western music. It's typically only danced at specialty square dancing nights at bars and community centers.
Interaction
Line dances to songs like "Cha-Cha Slide" and "The Hustle" are typically already known by the dancers. And those who are unfamiliar with the dance steps can join in and easily pick it up just by watching the other dancers. Square dancing is a bit more spontaneous. According to square dance caller Charlie Pergrossi, sequences are generally determined on the spot. Dancers have to pay close attention to the caller to know what to dance next.