What's the difference between 숫자 and 수효?

ANSWER: One refers to numbers in general, and the other to a specific number of things or people.

Tonight I was reading about the Tripitaka Koreana, which is a giant collection Buddhist scriptures that are stored at South Korea's Hapcheon Haeinsa (합천 해인사), when I came across the word 수효 (數爻) and wondered why the writer wrote 수효 for "number" instead of just 수. By the way, Hapcheon Haeinsa (합천 해인사) is a Buddhist temple that is located in Hapcheon County (합천군) in South Korea's South Gyeongsang Province (경상남도).

The Korean name for the Tripitaka Koreana is 팔만대장경 (八萬大藏經), which literally means "The Giant Collection of Eighty Thousand Scriptures." The reason Koreans call it the "The Giant Collection of Eighty Thousand Scriptures" is that it is a collection of Buddhist Scriptures carved on more than 80,000 wooden printing blocks, which would be the equivalent of about 330,000 pages, or 1000 books with 330 pages each. So, the 80,000 (팔만 八萬) does not refer to the number of scriptures but to the number of wooden printing blocks on which the scriptures are carved.

Anyway, here is the Korean sentence in which 수효 appeared:

팔만 권의 경전을 일컫는 말로 알기 쉬우나, 사실은 불경을 새긴 목판의 수효가 팔만 장이란 데서 나온 이름이다.

"It is called 80,000 volumes of Buddhist scriptures for convenience sake, but the name actually comes from the number (수효) of wooden printing blocks on which the scriptures are carved."

So, why did the writer write 수효 for "number" instead of just 수 or 숫자?

First, the Korean word 숫자 (數字) literally means "counting (數) character (字)" and refers to numbers in general, not to a particular number, such as 80,000. My Korean-English dictionary translates 숫자 as "figure" or "numeral" and gives examples that use it in a general way, such as 숫자상의 잘못 for "numerical errors," and 정확한 숫자 for "precise figures." So Koreans wouldn't, or shouldn't, write  "목판의 숫자가 팔만장" to refer to the 80,000 wooden printing blocks, but rather "목판의 수효가 팔만장."

Second, I think 수 (數), by itself, could have been used to refer to the number of wooden printing blocks since it can mean "number" and is synonymous with 수효, but since 수 (數) can also mean "luck" or "fortune," maybe the writer used 수효 (數爻) to avoid any confusion.

Finally, the 효 (爻) in 수효 (數爻) means "trigram" and refers to the trigrams found in the "Book of Changes," and trigrams are essentially "number symbols," from what I understand, so, I'm guessing that 수효 (數爻) could literally translate as "counting (數) numbers (爻)."

The definition of 수효 (數爻) in my Korean-Korean dictionary is 사물의 낱낱의 수, which can translate as "the [total] number of individual things," but I think that the definition should also include "people" (사람). That would change it to 사물과 사람의 낱낱의 수, which could translate as "the [total] number of individual things and people."

From Dong-A's Prime Korean-English Dictionary

From Dong-A's Prime Korean-English Dictionary

From Dong-A's Prime Korean-English Dictionary