I'd say simply comparing your work to someone else's is a very broad topic.
The first thing I would do would be to pick a piece of mine from a common genre, or a genre of particular interest to myself, eg. suspense-based horror. I then would choose a few particular films, or sound designers renown for their work in these genres who I gained inspiration from, and start from there.
Pick apart your own piece, layer by layer, describing what you were thinking and where you drew inspiration from, for each part. Describe your process and methods and continually cross-reference with the 'case study' films and artists you've chosen, discussing how similar things were achieved in these other pieces, eg. particularly effective off-screen effects, use of silence, ambient backgrounds etc.
You will not be able to discuss everything in each piece, so plan and structure what you intend to write about well. Don't compare all of your piece with all of another three pieces; simply compare where appropriate: "in scene ABC I left a period of silence because XYZ. A similar technique was used by Joe Bloggs in Horror Movie..." and so on.
Wrap the whole thing up with a conclusion on your own methods and techniques, and possibly some self-crtitique and thoughts for the future.
I think it's important to remember, on pieces like this, that there's no real right or wrong answer. As long as you back up your discussion and opinions with plenty of referenced material then you should be safe!