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The difference between mechanical keyboards and membrane keyboards is very big, from the structure, design, principle are not the same, that is, the shape is almost ~~~~ and the four you give, the latter three belong to the membrane keyboard, the specific content please search for yourself.

Ordinary keyboards do not say ~ ~ ~ ~

Chocolate keyboard is from the shape of the keyboard, because the shape of the keys like a plate of chocolate, so named, the shape of the ordinary keyboard smashed flat look, belong to one of the most common ultra-thin keyboard shape. Another common thin profile is the silo style, which is usually found on the keyboards that come with Apple laptops.

The scissor foot is the ultra-thin keyboard, a keycap design, but also the keycap design classification of a category, the most common in the laptop keyboard (because this structure keyboard can be made very thin), the other crater type, the palace column type, and so on. In terms of shape, the two most common ultra-thin, chocolate and silo type have the use of scissor feet, so scissor feet and chocolate are two different categories under the classification method, can not be directly compared.

Mechanical keyboards are not yet ultra-thin, mainly due to the trigger structure decision (MX axis).

Please search on your own for specific details, key terms are basically given.