Which brand is good in what?
 

I'm interested to know what's special or the strength of a given brand, or the different characteristics of different bike brands. For example, some may be good in road bikes, some in hybrids; some may tend to have thick frames(?), some may have more classic looking, etc., etc.. Is it possible to make some loose observations on this?

Bike = a frame + a fork and a bunch of parts attached to them.
Its just paint, and a contract to have it made in some design

the components are a choice by the product manager,
bike companies have a range of models, to suit most consumers..

materials used have design requirements ..

read more until you have a few narrow specific questions.
then come back.

That's like whats better apples or oranges. There are no firm answers, just lots of opinions. Bikes are made of standard components, so if you match the specs, the remaining variable is the frame. There's also a matter of your budget, there's no need to compare $5,000 bikes if you're looking for a basic set of wheels.

Try to pin down the general area you're interested in, then use the internet to search for reviews or comparisons. Also browse the various bike shops locally to get a general idea. If you're not knowledgeable this is the best way to start, and possible finish, since otherwise you not in a position to intelligently analyze the advice you'll get.