

Shelf space.
That is, filling the shelves at the supermarket with the illusion of choice. Manufactures want the most shelf space they can get so that you spend the most time looking at their product, but a huge shelf of the same product is also a turn off, so variations of a products are churned out. E.g. sensitive, no fragrance, varied fragrances, coloured hair, curly hair, 2in1, 3in1, pre-rinse, post-rinse, ad infinitum.
This is not intended to invalidate all the other replies talking about some of the technical differences (real or perceived).









I’m betting that part of trump’s fascination with Greenland is because of the mercator projection.