Public Intoxication is a misdemeanor offense that requires the state to prove the person was so intoxicated that they are a dnager to themselves or the public.
Public Intoxication is different from merely being "under the influence". Under the influence in the context of a DUI means that the individual is merely impaired to the degree that they can no longer drive with the caution characteristic of a sober person. Public intoxication requires a higher degree of impairment, to the point you are now a danger to yourself or someone else.