"Favorite" vs. "favourite"
They have the same meaning, but favourite is used in British English, Australian English, New Zealand English and Canadian English whereas favorite is used in American English.
It's not a stupid question. No single person knows everything.
The "ou" is a common British spelling, whereas in American English, we simply use the "o." For example:
- favourite vs. favorite
- colour vs. color
- labour vs. labor
- honour vs. honor
..and so on.