1. may i borrow this book? - sure. just remember to give it back in a week. 2. may i borrow this book? - sure. just remember to give it back within a week.
in this short dialogue, does 'in' mean 'within'? or are both different?

They are both different because, within a week they are supposed to give it back before it is more than a week, it is a regulation, while in a week, you can go a bit higher with a few days.

Some cultural backgrounds have different superstitions or customs, this can play a part in how they decide things. superstitions are important to a culture for example, an asian culture has a superstition about women putting their purses on the ground their money will be gone, therefore people in that culture try everything they can to not let their purse touch the ground in fear of it being true. also like how we avoid walking under ladders in fear of bad luck. customs may also play a key role a custom also know as a tradition, is something people in the culture have been doing for generations as a quick example, if a family has a necklace that the family's mother passes it on to her daughter in so on it's a custom in that family.