Sounds where the spelling visibly differs
"し" (shi/si), "ち" (chi/ti), "つ" (tsu/tu), "ふ" (fu/hu), and "じ" (ji/zi) are classic examples of sounds spelled differently under Hepburn versus Kunrei-shiki.
Its relationship to school education
Elementary school romaji instruction is based on Kunrei-shiki, but most of the spelling seen in everyday society is Hepburn — knowing that both exist makes it easier not to be thrown off by the difference.
Frequently Asked Questions
Can I freely choose how my name is romanized on my passport?
In principle, it follows the Hepburn system, though for certain elements like long vowels, exceptions are sometimes permitted under specific conditions. Check with your passport issuing office for details.
Which is correct, Kunrei-shiki or Hepburn?
Both are official systems established by the government, and neither is superior — they're used differently depending on the purpose and context.