Seeing is believing

hi :)
I am a learner of English.

there is one more question.

in gerund & Infinitive construction, I can't find definite answer.

"seeing is believing" and "to see is to believe" is definitely equal?
there is no difference?

I think that meaning is same but there is subtle, different nuance..

if you have a fine answer. please reply this question.
and have a nice day..:)

The two expressions mean the same thing, but only "seeing is believing" is a traditional one, or as we call it, an "old saying."