"Rap" and "Hip Hop" generally overlap and refer to subsets of R&B/Urban music. However, not all rap is hip-hop and not all hip-hop is rap.
1. Not All Hip Hop Is/Has Rap
Historically,
Hip Hop comprises
4 elements,
1 of which is rap, as outlined by DJ Afrikaa Bambaataa.
The
four elements of
Hip Hop are DJing, MCing (a.k.a. rapping), B-Boying (a.k.a. breakdancing) and graffiti writing.
http://en.wikipedia.org/wiki/Hip…
Old schoolers rapped about all these elements, although hardly any commercial rappers talk about graffiti writing anymore. Now the most famous graffiti writers are Banksy and Shepard Fairey. They are not hip hop.
Some of the greatest hip hop music has no rapping at all, consisting only of beat mixing, sampling and scratching.
2. Not All Rap Is Hip Hop
Rap can be any kind of speaking, typically over a beat but not always.
People have "rapped" since long before hip hop. Hippies rapped. Parents in after-school specials invited their fictional kids to "rap" about drugs, sex, puberty, etc.
Blondie's "Rapture" had a rap, but it is not hip hop. It's disco or punk or pop.
3. The "Rap" Genre Is a Subset of "Urban" and "R&B/Hip-Hop" in the Music Industry
According to
Billboard (the music industry Bible), a Rap single can either be in the Hip-Hop or urban dance/upbeat pop genres.
Nowadays, many people generally understand "rap music" to mean hip hop music that includes rapping of the likes of Eminem, Jay-Z, Kanye West, the rap interludes in Black Eyed Peas songs.
Billboard combines several charts under the
R&B/Hip Hop primary-level category. These are a continuation, in various forms, of urban charts since
Billboard's "Harlem Hit Parade" chart in 1942.
http://en.wikipedia.org/wiki/Bil…
Billboard,'s
Hot Rap Songs chart is the product of an algorithm of Hip-Hop and radio stations playing "Rhythmic" (urban dance, R&B, upbeat pop). Singles on that chart can be, but are not necessarily, hip hop. For example, "O.M.G." by Usher has rapping by
will.i.am, but is dance, not hip hop.
http://en.wikipedia.org/wiki/Rap…