In general eagles tend to be significantly larger than most owls, though certain types of owls can grow to be as large as eagles. When it comes to sheer size and strength, eagles definitely come out on top. Eagles also have a larger wingspan than owls, though both of these animals are very efficient aerial hunters when it comes to land prey.
Another one of the more glaring differences between owls and eagles is that owls tend to be far-sighted while eagles are near-sighted. While for the most part owls do not grow to be as large eagles, this is not always the case.