Actually, this is the web novel so it may have some differences with the LN.
Ok, it is completely different!! But not bad per se.
Completely different as in same characters different story line? or just a different direction?
ah very differnt.. is the LN version closer to the manga?
Different storyline. The elements and characters are probably alike but the sequence of episodes seems to be different.
Unfortunately, I didn't find the translation for the LN only the WN so I can't say.
To whomever may interest:
http://www.novelupdates.com/series/that-person-later-on/