In the Datukatha Puggala Pannaththi some of these terms are explained. I have translated them (and some others) to English from the Sinhala and Pali based on my understanding.
Ubathobaga Vimuttho – Someone who experiences the Ashta Vimokka while living and eliminated all defilements (ashrawa) through understanding (pragna).
Pragna Vimuttho – Someone who does not experience the Ashta Vimokka but has eliminated all defilements through understanding.
Kaya Sakki – A person who experiences the Ashta Vimokka while living and has eliminated some of the defilements.
There is no explanation about a Chetho Vimuttho person. However there is mention about Cheto Vimutthing and Pragna Vimutthing, where it is mentioned that a person who still has defilements has not experienced chetho vimutthing or pragna vimutthing. In all the explanations, it is mentioned that all defilements are eliminated through understanding (pragna).
From these explanations I feel that a Chetho Vimuktha Arahanth may be actually referring to a Ubathobaga Vimutta person.