Both of these versions stick to Shakespeare's language in verbal presentation. Although they both present some language out of order, it is fairly close, the 1968 version closer than 1996. They vary in their visual interpretation, which significantly contributes to ideas.
First, costuming and setting of the 1968 version make great effort to mirror what would have been worn in Shakespeare's original plays put on at the Globe Theatre. In the 1996 version, the director sought to identify with a current generation and did so by replacing swords with guns, employing fast-paced moving images, using color symbolically, and giving characters gesture-direction that assisted the language. This last move in particular helps teenagers understand the difficult language they are so far removed from. The ideas of love, infatuation, violence and teenage rebellion are easy to interpret for today's teens when those gestures are inserted.
As one who instructs this text, I feel the 1996 verion well-assists the comprehension for students.