What is the difference between lighter than air and heavier than an air vehicle?

"Lighter than air" aircraft are lighter than air! The most common are blimps. They do not rely on wings to generate lift. They contain a lighter than air gas (ex:helium) that lifts the craft into the air when ties to the ground are released.

"Heavier than air" aircraft are the opposite. They rely on wings to generate lift to get into the air. Common heavier than air aircraft are general airplanes you see in the sky everyday.