In pcs, all laptops are considered portable, but not all are ultraportable.

Ultra-portable laptops, actually have specific dimensions, weight and other characteristics they have to reach to be called that (Intel pushed the standard several years ago to earn the badging for OEM devices). Devices like Asus Zenbook or Lenovo Yoga are considered this.

In handheld, I absolutely wouldn’t call any current handheld pc ultraportable. The Switch and anything thinner/lighter would probably be the gate to using the classification.