Setting time format preference in unix (Mac-Terminal)
Using GNU ls, on Linux, there is a --time-style flag you can use to specify one of a few pre-defined time types, or specifying a completely custom +FORMAT style like the date command accepts. However, BSD ls, which Apple ships, does not support this flag.

I've seen similar discrepancies in commands like date and tar as well, all rooted in the differences between the GNU and BSD variants.