The Sigh of Haruhi Suzumiya Part 4 (manga)

The Sigh of Haruhi Suzumiya IV is a chapter of the Haruhi Suzumiya Manga, volume 6.

Differences

 * Shamisen's conversation with Kyon, Mikuru Asahina and Itsuki Koizumi takes place before Kyon reconciles with Haruhi, instead of after. At this stage, Shamisen had yet to be recruited in the anime or light novel.
 * Koizumi informs Kyon about the increasing numbers of people in costume during preparations for the arts festival. In the anime, Kyon notices this without being told.
 * The "it was a dream" ending is visualized by Koizumi as Mikuru waking up from said dream. No such visualization happens in the anime or light novel. This proposal also takes place before Kyon reconciles with Haruhi.
 * After their fallout, Kyon first sees Haruhi in class with her hair tied in a ponytail. He tries to initiate conversation, but Haruhi unties her hair and storms off. The light novel does not clarify the state of Haruhi's hair until Kyon goes to see her at the club room, while in the anime, Haruhi's hair remains untied during class.
 * Mikuru gives Kyon the café voucher before he reconciles with Haruhi.
 * Yuki Nagato communicates her stance on the situation at a corridor, instead of the club room.