The words used interchangeably in referring to the beings themselves, seraph experimentation has resulted in human bodies becoming hosts for seraphs. Their extraordinary powers are helped to be kept in check by a demon, and for good reason since seraphs' have world ruining capabilities.
In chapter 102 cloaked seraphs appeared to support Yu in his goal of rescuing Mika. Appearing in chapter 108 and 109, they helped fend off Sika Madu himself. 113 and 114 is a reminder that seraphs target who they regard as sinners.
Chapter 123, and 124 revealed a gargantuan civilization of seraphs where many cloaked ones existed with homunculi. The seraphs at this time heralded Sika Madu as their king.
A greatest revelation yet on these rarely seen beings was in chapter 126 where humanoid appearing seraphs were revealed. Their appearances coinciding with flames that emerged from a group of cloaked seraphs after photons were displayed, it stands to reason that the cloaked seraphs would each have a distinct form. Demons can appear as a mass of shadow, yet do have true forms they can assume. Given the surprisingly similar traits that have been displayed, it's possible every one can change from a cloaked figure with fire in the place of their heads as a human appearing seraph.