What was the cultural difference between Jerusalem and northern Israel in Bible times?
Jerusalem, site of the Temple and priestly activity, was more cultured and educated, especially in biblical matters. Northern Israel, including Galilee, was more rural and less highly educated; most people were farmers and sheep herders, so Galileans often stood out as culturally distinct.
Les explains that there was a culture situation between Jerusalem and northern Israel. Jerusalem, where the Temple had been and where the priests and their activity were centered, was more cultured and more educated, especially in Biblical things. By contrast, northern Israel was more rural and not as highly educated; most of those people were farmers and sheep herders. Because of that difference, the Galileans probably just stuck out like a sore thumb.
And they were all amazed and marvelled, saying one to another, Behold, are not all these which speak Galilaeans?