The food critic and author Mark Bitman believes there actually is a difference between thick and thin asparagus spears, and he contends it’s more than just cosmetic. That doesn’t mean one type is preferable to the other, though. Both have their strong points.
Thick asparagus should be peeled with a vegetable peeler by laying each spear on a flat surface and giving it a few swipes, he cautions. Thick spears are more substantial. When peeled, however, they can be cooked for less time, allowing them to remain colorful and crisp. These thicker spears are also great for grilling, steaming, or poaching.
Thin spears are less substantial but do not require peeling and can be stir-fried without parboiling. They are an ideal choice when making puréed soup, and because thin asparagus is less fibrous, it is preferable for roasting as in this quick recipe from Chef Valerie Augustine. Quick but so delicious we found it impossible not to pick from the pan while waiting for lunch to be served!