A hemisphere is half a sphere
Sphere is whole a hemisphere is not
A sphere or torus (a donut).
Sphere, torus, moebius strip
A blob, an ellipsoid, a torus (doughnut), a sphere
A hemisphere is half a sphere
Sphere is whole a hemisphere is not
A sphere or torus (a donut).
An ellipsoid, a sphere, a torus to name a few.
A sphere, an ellipsoid, a torus (donut), an irregular blob with no pointy bit.
A sphere, ellipsoid, torus (doughnut), and many more besides.
Sphere, torus, moebius strip
A blob, an ellipsoid, a torus (doughnut), a sphere
A sphere has 0 vortex and a cylinder has 2 faces
A sphere, a cone, a section of a sphere or ellipsoid, a torus (doughnut) sliced by a plane perpendicular to its axis, a paraboloid. These are some examples.
Topology is the study of objects (often surfaces in 3D) where details like position, shape and curvature are unimportant. Two topological objects are considered equivalent if they can be stretched to look like one another. An example of two different topological objects are a sphere and a doughnut shape (torus); the sphere cannot be stretched to look like the torus because it doesn't have a hole and the torus does.
They are very different, as a square sphere is impossible. The difference is that a square pyramid exists, whereas there's no such thing as a square sphere.