As adjectives the difference between scatty and scathy
is that scatty is (slang|british) scatterbrained; flighty while scathy is mischievous; vicious; dangerous.
scatty
English
Adjective
(er)
(slang, British) Scatterbrained; flighty.
scathy
English
Adjective
(en-adj)
Mischievous; vicious; dangerous.