Hey Chedapalooza...I would consider the carnitine-l-tartrate to be the main defining ingredient which sets the powdered formula apart form the others, along with the supporting ingredients for the carnitine. Carnitine-l-tartrate is great stuff. Not only does it have it's place in thermogenics but it's also great for pre-workout use for a variety of reasons including vasodilation and hormonal response.
An additional benefit with the powder is that it is ideal for pre-workout use because it hits hard and fast.
I'll be getting some myself soon for morning cardio. I normally take the caps, then go back to bed for about 30 minutes but with the powder by the time I get to the bike for cardio it'll already be kicking in.