How does the 1999 film Hamlet by the Royal Shakespeare Company differ from the play Hamlet written by William Shakespeare?
There are many films made of the play Hamlet. Here is a link to the version I would like to compare to the play:
Your question isn't as simple as it might first appear to be. The main reason for this is that, technically, this is a "filmed" version of Hamlet, but it is performed by a theatre company -- The Royal Shakespeare Company -- and produced for television entirely on a soundstage that simulates the environment of an indoor stage production. This version lacks the switching between Interior and Exterior locations more common in an actual film adaptation of the play. (It was adapted for televison in 2009 for airing in 2010, not in 1999.)
This sort of re-staging of a theatrical production for the camera from different angles and with different camera placements does make the play read like a "film," but this production falls more closely into line with the made for television series for the BBC called "The Shakespeare Plays" that were made in the 70's and 80's.
It is important to establish that this is a filmed version of a stage play, because it affects your question, making it less possible to contrast it with the play itself since it is the play. The choices of costuming and setting are not "changes" to the script of the play, since every play must have these elements chosen for production.
One of the elements that I see that would allow you to contrast this filmed version of the play with the one presented theatrically, is that there are camera angles that allow the audience to perceive only what is chosen in any given moment. For the audience in a theatre, where to look is a choice that each viewer makes, not something chosen for him or her by a camera. So, for example, in the opening scene, Barnardo is shot walking his post as guard from above, so that it appears to be some sort of surveillance footage. This effect would definitely not have been possible onstage.
Another obvious difference is that the soliloquies that Hamlet shares with the audience in a live production when he is alone onstage, here lack that direct connection to the audience.
For the most part, this is a recreation of a staged production of Hamlet, and so, in the choices of action, costuming and setting, is not possible to contrast with the play since it is, in fact, the play itself. I have provided a couple of links to more information on the transferring of this stage production to the TV screen below.