Difference between sign and notice

Test No. [color=blue]incompl/advan-73 “At the End of the Day (2)”, question 5

put a outside your door stating: Do not disturb - having 40 winks.

(a) notice
(b) board
© sign
(d) tablet

Test No. [color=blue]incompl/advan-73 “At the End of the Day (2)”, answer 5

put a notice outside your door stating: Do not disturb - having 40 winks.

Correct answer: (a) notice

Your answer was: [color=red]incorrect
put a sign outside your door stating: Do not disturb - having 40 winks.
[size=200]_________________________[/size]

what would be the difference if I used “a sign outside” my door…

Notice is needed here because it would provide a specific piece of written information of a temporary nature like wet paint/no milk today. Sign would indicate a direction or a place to go to or an official designation like no smoking, which would be permanent.

I gotcha???