\caps used to change the font shape to caps, which is available in eg
ccm, but not in CenturySchoolBook. So when the later was the default
font, \caps had no effect.
A hackish \smallCaps was developped, which change lower case
letters to
smaller upper case letters.
So at some point, the two were different commands, one working only
with
fonts that had the caps shape variant, and the other, more ugly,
but which
works with the default font.
In the end, because of the numerous questions about why \caps has
no effect,
it was decided to be made identical to \smallCaps.