In terms of spelling, one has a u at the end and the other has a macron over the o, which is right...
arigatou or arigatō ??
arigatou and arigatō

(deleted)
August 18, 2008

Sayaka-Matsuura
August 18, 2008
Konnichiwa!
arigatou or arigatō are both correct.
You will surely see them both used in different texts.
:D