They aren't synonyms really! UNinhabitable means 'can't be lived in'. InhabitED means someone is living in it. Habitable is what we say when it CAN be lived in. Inhabitable means it can be lived in, but it isn't very common usage because it's confusing. You can tell by Google hits. 1.2 million for inhabitable, 5.9 million for uninhabitable and 38 million for habitable. So if you mean someone can live in it, use habitable, not inhabitable. It's more common. And if you mean they can't live in it, use uninhabitable

They are synonym; both of them mean fit for habitation

habitable - means able to be lived in. inhabitable - means not able to be lived in. In my experience, both of the above words are normally applied to a place where a human could live. But they could be used in application to animals. The prefix 'in' when applied to a range of words means 'not' Animals are found in a particular habitat and occupy an ecological niche within that habitat.

Habitable : Able to be lived, as Earth is Habitable . Inhabitable : Not able to be live in, as Mars is Inhabitable.

Zander, The adjective 'habitable' is derived from the verb "to habit" meaning "to live in." It is an archaic or rarely used verb, although I have come across this word in modern prose several times. -18 May 2012 – Many houses were inundated with water and many of them lost their belongings as they habited the low lying banks of the river. The logical opposite of habitable "inhabitable" was once used with its negative meaning. It is now considered obsolete, meaning not only that it is archaic, but that its use would be misinterpreted. -1674 People towards the North, living in a climate almost inhabitable. ----------- The modern adjective 'inhabitable' is derived from the verb "to inhabit", which means "to live in." -The house is in such poor condition that it is barely inhabitable. The opposite of inhabitable is "uninhabitable." -Flooding made the building uninhabitable. --------- The original usage of habitable/inhabitable agrees with the Longman definition, but modern usage has expanded the meaning to include animals. -if a place is inhabitable, people and animals can live there...Macmillan English Dictionary for Advanced Learners -Several hundred species of birds inhabit the island...Merriam Webster Advanced Learners Dictionary -habitable ....fit to inhabit...Collins Thesaurus of the English Language -Winter can be tough on birds that don't migrate south to find more habitable conditions.