What is the difference between orbital and suborbital spacecraft? The difference is speed. An orbital spacecraft travels too fast to fall back to Earth (and is therefore able to complete an orbit around Earth). Think of throwing a ball: if you throw it softly, it will travel a little distance then fall to the ground. But the more power you put into the throw, the straighter its path above the ground is, until it starts losing speed.
An orbital spacecraft flies at such a high speed that it is able to maintain its distance from Earth. A suborbital spacecraft cannot go fast enough to achieve orbit.