Essential difference: ghost dance: it is a kind of party dance rising in recent ten years, which expresses music through dance steps.
Poppin: It appeared in 1970s and belongs to funky dance.
Musically: the music of ghost dance is basically disco music or music derived from disco music. Poppin's music is a dance that was born when soul music appeared, and it is difficult for breakin and lockin to interpret soul music. His music is divided into gfunk music and pfunk music.
History: Generally speaking, Ghost Step is based on house, and poppin is based on the development of music and lockin.
As for the relationship you said, maybe some things of ghost dance refer to poppin, but there is no specific connection.
As for ghost dancing and sliding, the difference is big. They are not the same thing at all. Look at the video of House and cwalk, and you will probably understand. Although the same thing is used, it is completely different.