There's a few significant differences here. This is a printf that only happens in debug mode; dbg is something that takes an expression, returns that expression, and will print out its filename, line number, and a pretty-printed version of the value.

For an example of how this plays out, I had some code:

    let x = y + z;

I wasn't sure what y was, so I was able to

    let x = dbg!(y) + z;

this is much easier to insert into (and remove from) existing code. Plus, you don't need to write the formatting code.

Basically, what you posted is in the same genre of thing, but is very different in a lot of meaningful ways.