Mac storage basics · Disks, APFS and formats
What does case-sensitive mean for APFS, and should I use it?
Short answer: Case-sensitive APFS treats Report.pdf and report.pdf as different files. Many Mac apps expect the default case-insensitive format, so use that unless a tool requires otherwise.
On a case-sensitive volume, Report.pdf and report.pdf are different files; on the default case-insensitive format they're the same name. Some developer workflows want case sensitivity, but many Mac apps assume the default and can misbehave on a case-sensitive volume.
Unless a tool specifically needs it, use the standard (case-insensitive) APFS. It can't be changed later without erasing.