A cloaca is a single hole that contains the anus and genitals, not a penis. It's just a hole most of the time. There are times when this isn't the case, such as with alligators and ostriches, those weirdos.
A genital slit is where only the genitals hide, while the anus is separate and visible. Like a dolphin.
If a male character suddenly has a single hole visible, and is either a bird or reptile, (which have regular hole-type cloacas like 95% of the time), don't assume it's a female and improperly tag an image as rule 63 or whatever; just assume it's trying to be a bit more anatomically correct.
I always see these tags being used improperly and it's super annoying. D:
kthx
Updated by ShylokVakarian