As adjectives the difference between unobtainable and unreachable
is that unobtainable is not able to be obtained, acquired or reached while unreachable is unable to be reached; impossible to attain.
As a noun unreachable is
a person or thing that cannot be reached.
unreachable
English
Adjective
(-)
Unable to be reached; impossible to attain.
Noun
(
en noun)
A person or thing that cannot be reached.