Laptop Keyboard Replacement but not exactly - Question.

moulderhere

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I have a laptop that I'm replacing the keyboard. I have found 2 keyboards:

1 is exactly the same as what I have but $79.99
2nd keyboard is same design but the secondary keys (the FN keys all across the keyboard) are in different places and or I don't have the options for things like turning down laptop brightness on keyboard. This is $25

Does anybody know if the keyboards that come with laptops are pre-determined by manufactor as to key assignment? Like would the replacement keys even though they say something else on the label would be what the old keyboard has them as????

Thank you and have a bodacious night!