p.s. Please disregard the last paragraph, because I think I made a mistake. 「違う」followed by a noun is "another form "rentai kei (連体形)" of the verb. Sorry for the confusion.

When 「違い」 is followed by 「ます」or 「ません」, then it is the "i-form" (or ren-yo kei 連用形) of the verb 「違う」(to differ, to be different). In all other cases, 「違い」is a noun (when followed by 「が」,「は」,「の」,「です」 etc.) それは違います。　=　That's different. それが違いです。　=　That's the difference. This is quite confusing, but there is no wonder. Many (but not all) of Japanese verbs derive noun forms by using the "ren-yo kei" Some examples include: 喜ぶ(to be pleased)→喜び（pleasure） 誘う(to invite)→誘い(invitation) 受け付ける（to receive, to accept）→受付（うけつけ）(acceptance, reception) For your information, if 「違う」is followed by a noun, then that is of course an adjective. 違う歌 = different song Good luck!

違い是名词,意思是区别,差异,这个词好像不是具有形容词意思的名词. 用法可以是这样:性格の違い　違いが出る 这句话中用的是違う,是动词形式. 違う是动词,自动词,这句话用的是动词形式.