A computer is a tool, like a hammer. Have you used different hammers before? There are differences between different brands, and those differences are typically subtle. Computers are similar; they're mostly identical, and the differences between them (to the "consumer") is very subtle. If you buy your near-blind grandfather a 13" macbook for reading the news, yes, things will go badly. However, you don't need to look at the specs to know that.
I don't really know what your point is re: NAV.