"Old school Rap" and what may be called "contemporary rap" enjoy some general stylistic differences. Today, it is common for rap lyrics to be contoured around the rhythm of the song and to be less constrained by the beat. This was not the case in early hip hop where lyrics often stuck closely to the tempo and punctuated the beats of the piece. Old school tracks usually display a more economic sense of structure where stress was placed on an art that was entertaining and good-natured rather than on an acute sense of lyrical skill. This in part gave early rap that rollicking "block party" feel.
Rap production often draws from many different musical styles and sounds to accentuate different tracks. The same is true for early hip hop as it owed much to the musical atmosphere of the 70s and 80s. Disco beats and furiously funky rhythm grooves dominated a good deal of the instrumentation. A great example of this would be the Fatback Band's "King Tim III." Electronic beats were often accompanied by rolling base-lines and on occasion parts for horns. Also, sharp breaks, most associated with rock music, were found in a number of these early efforts.
Recent rap artists throughout the 90s and the first decade of the 21st century typically infuse some level of social commentary into their lyrics. Old School poetry focused more upon lighter themes of partying and dance. At points off-beat and ridiculously clever, artists like The Sugar Hill Gang injected an energy of freedom into undeniably fun recordings. However, to say that social content was absent in Old School Rap would be an error. Early rap icons like Grandmaster Flash and the Furious Five displayed these concerns in some of their biggest hits like "The Message." Social issues did not at all escape early hip hop and rap artists, yet they were not the predominant theme.
The transitions between vocals became great sights for musical samples to be introduced, a growing trend by the mid 1980s in the music of artists like Doug E. Fresh and Run DMC. While not necessarily "Old School" by some definitions, the Brooklyn-bred Beastie Boys are widely recognized as exploding the potential for sampling in their sophomore effort "Paul's Boutique" where over one hundred of them were used in the album's production.
By the late 1980s, Old School was transformed by new trends. Production economy was giving way to advanced production techniques and introspective lyricism. The rapper became the epic storyteller, the artist with the inside track on society's ills and the ability to relate them with new meaning. The previously fun-hearted escapism became a medium for speaking about issues as pertinent as poverty, education and race. These transitions were not necessarily bound to happen, but illustrate rap's artistic flexibility and its openness to different musical styles, ideas and lyrical content.