Rich Jaroslovsky
Bloomberg News

The one-two punch of Appleís iPad and Microsoftís Windows 8 has led to a new class of personal-computer hybrids that look and work like regular laptops, but whose screens pop off to become fully functional tablets.

Iíve recently been using two that share this convertible form but represent opposite ends of the pricing spectrum.

The $1,200 Samsung ATIV Smart PC Pro is a powerful, premium model competitive with the likes of Microsoftís own Surface Pro. Hewlett-Packardís Envy x2 is budget-priced at $699 and less potent ó yet more successful in achieving its modest aims.

There is nothing really bad about the ATIV Smart PC Pro. (Except maybe for the name.) It just feels compromised as both a tablet and a laptop.

The ATIVís technical specs are fine: Itís powered by an Intel Core i5 processor and includes four gigabytes of memory and 128 gigabytes of speedy solid-state storage. The 11.6-inch screen is capable of delivering full 1080p high-definition video.

The ATIV also comes with Samsungís S Pen and the software to use it, so you can take notes or otherwise scribble onscreen in tablet mode. But you arenít likely to want to do that too often, or for too long. The ATIV is simply too heavy and ungainly ó at 1.9 pounds undocked, itís almost 50 percent heftier than Samsungís similarly stylus-equipped Galaxy Note 10.1, which runs Googleís Android operating system.

The battery life, about five hours give or take, is poor for a tablet. Itís a little more acceptable in a laptop, but the ATIV suffers in that mode from ho-hum looks and design. With the keyboard attached, it weighs more than 3Ĺ pounds and feels top-heavy with the lid open.

Samsung has made some truly gorgeous and capable Windows PCs, like the Series 9, a traditional clamshell laptop. The ATIV suffers by comparison.

On looks alone, Hewlett-Packardís Envy x2 has Samsung beat. The brushed aluminum and wedge shape evokes Appleís MacBook Air, and the HP costs hundreds of dollars less than either of them.

Thereís a reason itís so much cheaper: Itís built around an Intel Atom dual-core chip that has considerably less processing oomph than the Core i5 used in those other machines. It also comes with only two gigabytes of memory and 64 gigabytes of storage, about the absolute minimum you can get away with these days in a computer running Windows 8.

If you donít need much computing power, though, the Envy has some real attractions.

Itís more usable as a tablet than many competitors. Most hybrids should probably just be thought of as laptops with detachable screens; you wouldnít really want to use them as tablets for any length of time. The Envy is an exception. The 11.6-inch screen is thin and light ó a third of an inch and 25 ounces.

It accomplishes this by using two batteries, one in the screen and the other in the keyboard.

The seven-hour battery life for the tablet alone is better than the ATIVís, but falls short not only of the iPadís nine to 10 hours, but also the eight hours from Microsoftís Surface RT.