The two main differences difference between use and require are

• use is done during the initial compile phase whilst require doesn't happen until it is encountered during program execution.
• require does not run the import function.

The scope is the same for both, that is from the time they are first run until program exit.

Typical usages include

sub rarely_called {
    require Expensive::Module;
}
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sub not_backwards_compatible {
    require 5.010_000;
}
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require for pragmata probably won't do what you think since import is not run.