Is there a difference between ほんとう (hontō) and ほんとうに (hontō-ni) when used alone as interjection or question?


As the equivalent of Enlgish "Oh really?" / "Yes really." as lone utterances I
seem to hear both "本当" (hontō) and "本当に" (hontō-ni) in Japanese - is there a
difference?

It seems that hontō is a noun and -ni changes it into an adverb but that this
doesn't really matter for the purpose of such simple utterances. Am I thinking
along the right lines?




There is no difference in utterances for both words, if you speak those alone.

But if you add some words after that, you might need to use "本当に~" to get
correct grammar.




There is no difference in utterances for both words, if you speak those alone.

But if you add some words after that, you might need to use "本当に~" to get
correct grammar.

