What's the difference between a "Keyboard Language" and an "Input Language"?

I see the same keyboard options underneath different languages, and it's confusing me...

What exactly is the difference between selecting an "input language" inside Windows, versus merely selecting the "keyboard layout"?

Solution 1:

Language includes things like is it right to left, or left to right, and the keyboard layout is just "when you press A, you get a" and things like that.

Solution 2:

@soandos has provided with a decent answer, here's more info.

Input language has primary and secondary parts.

Primary language (e.g., English) defines which code pages are to be installed, writing direction, numeric, currency, and date formats, and even common dialog layout.

Secondary language, as English (U.S.), defines common dialog texts, names for months and days of week, etc.

Keyboard layout specifically defines the ways how you type the text.
On your screenshot you may have noticed AZERTY keyboard. This is an excellent answer to your question. This layout defines a keyboard where the top row starts with A and Z instead of Q and W that you may have. So, although the system receives exactly the same scan code for a key pressed, it is recognized as A or Q, depending on an keyboard layout.

There are other keyboard layouts like Dvorak. There are languages when comma and period share the same key, and there are different layouts that vary based on which one is SHIFTed, and so on.

And, of course, there are plenty of keyboard locales for languages other that English. This article gives a good overview and also demonstrates variety of input layouts for Japanese.