What makes this dance recognizable? What is typical, distinctive or characteristic?

Kind of slow disco with large, soft, circular movements and a slight bounce.

A rokin 'good way - Shakin ' Stevens
It's my party           - Lesley Gore

Look who it is           - Helen Shapiro

It is a music style and dance (boogie) named after the first danchall where the music was played: "The Popcorn", opened in 1969 Vrasene in Waasland in Belgium. The name of the dance comes from a former hit of James Brown, "Mother Popcorn".

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The music is best described as a sultry mix of doo wop, especially soul and rhythm & blues, a little highschool rock & roll and cha cha cha.

I'm not technically and musically literate. An attempt to describe the difference between popcorn and disco. In the typical popcorn music you usually hear a prolonged odd beat, and a short truncated even count.

Popcorn oldies have rarely been hits, although they were often from famous writing duo's. The original single, EP's and LP’s are among the most expensive vinyl in the world.

On this music is danced somewhat lazy with the gentleman that as leader barely moves, while the lady is running the turns. It is a kind of slow disco. The couple starts in some loose open V shape, legs open in the viewing direction. Put on the outer foot near the interior, then the inner to the front, the outer back close and the inner to the front. With the inner leg every time you do a light bounce, and the basic step is finished. Further you fill with figures from the disco - boogie family.

Personally, I find it easier to explain and danced when emphasis is placed on count two and four. (Count e.g.: close-front-close-hind.)