[mistercow]

>The password "12345" has the same entropy as "b0g4p" but it would be a mistake to think they are equally secure.

Those do not have remotely equal entropy.

[mnarayan01]

At the byte level it does, which is presumably what the OP was talking about when saying that replacing characters with digits (uniformly) does not affect entropy.

[mistercow]

Maybe, but I would hope that's not what s/he meant, because that kind of entropy is basically irrelevant to password strength.