The shape of Earth is, in layman’s terms a spheric one. This is what we are being told from school, and in most part, it’s not a false claim. With this being said, the real shape of earth can be described in so many more ways.
Yes, in principle, Earth is spherical. This is the most simple way to explain our planet’s geometrical form. Its approximate radius is around 6371 KM, it usually varies between 6353 and 6384 KM, depending from where you measure it. This being said, the difference between our planet’s polar radius and equatorial radius is just 0,3 percent, so we don’t need to get a whole discussion started on the exact size.
So, going from our theory that our planet is not so spherical, it can be considered to be a rotational ellipsoid. This should be our best effort definition to describe the real shape of earth if we would want to be accurate and consider the above mentioned details. This new form tells us that our planet is flattened at the two poles and bulging at the equator due to the ongoing rotation it does around its own axis.
There are, however more complicated theories than this. Some people came up with a few controversies regarding the equator, if it’s in a form of a circle or ellipse. If the latter would be true, then our ellipsoid would be a triaxial one. A different theory invokes an even more complicated design. According to this one, a hollow would be present in our South Pole, accompanied by a higher ground around the same level in the North Pole. This would imply that the north middle latitudes would be flattened while the south middle latitudes would be more pronounced in a similar manner.
Another controversial theory regarding the real shape of Earth would imply that our planet is more a Geoid. This form is more used for scientific measurements. This way of representation uses the medium water levels as the main way to accurately pinpoint the vertical place of a certain location.
A few days ago, the image shown in the next image started making its turns around the internet, suggesting this would be a more accurate representation of the real shape of Earth. Thanks to brightside.me who shed some light over this matter, images similar to this one are only a representation of gravitational points around our planet. It is however exaggerated, but only to demonstrate us the differences found across the globe when it comes to gravitational forces, small differences as it seems to be pointed out.
A personal thought regarding the real shape of Earth? I would go with the term sphere when I would want to refer to a more broad definition. If we would however consider eliminating the waters which are filling our ocean plateaus, then yes, I would use the term Geoid to define our true planet shape.