What is the difference between using multiple -c options and concatenating the options with newline as the separator? (autocmd)

The following vim command lines show different results. Could anybody
help me understand why there is a difference? Thanks.

$ vim -T dumb -c autocmd\ BufWrite\ \*\ echom\ \"Writing\ buffer\!\"
-c w -c messages -c q
/var/folders/r7/bvmh1vvx41d63snvgbdz7bl40000gr/T/tmp.ZICAEj0GJD

"/var/folders/r7/bvmh1vvx41d63snvgbdz7bl40000gr/T/tmp.ZICAEj0GJD" 0L, 0C
"/private/var/folders/r7/bvmh1vvx41d63snvgbdz7bl40000gr/T/tmp.ZICAEj0GJD"
0L, 0C written
Messages maintainer: Bram Moolenaar <Bram@vim.org>
"/var/folders/r7/bvmh1vvx41d63snvgbdz7bl40000gr/T/tmp.ZICAEj0GJD" 0L, 0C
Writing buffer!
"/private/var/folders/r7/bvmh1vvx41d63snvgbdz7bl40000gr/T/tmp.ZICAEj0GJD"
0L, 0C written
$ vim -T dumb -c $'autocmd BufWrite * echom "Writing
buffer!"\nw\nmessages' -c q
/var/folders/r7/bvmh1vvx41d63snvgbdz7bl40000gr/T/tmp.ZICAEj0GJD

"/var/folders/r7/bvmh1vvx41d63snvgbdz7bl40000gr/T/tmp.ZICAEj0GJD" 0L, 0C

--
Regards,
Peng

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