The visible constellations are definitely different between the Northern and Southern Hemispheres. In general, at any given point on Earth, only around 50% of the sky will be visible. We can understand this by considering the atmosphere as a sphere around the earth. The sky any person can view at one point can be compared to a giant dome equal to half of the sphere. And because the Earth rotates, the dome we can see changes, unless one is sitting directly on the North or South Pole.