"Comparing boys to cauliflower" has no clear meaning, which may be because the shape of cauliflower is similar to some characteristics of boys, or because cauliflower is regarded as a nutritious and healthy vegetable in some cultures, which may be a compliment to boys who are similar to cauliflower in some aspects, such as health, nutrition, delicious and so on. But the specific meaning needs to be explained according to the specific situation and context.