Understanding Diels-Kranz (DK) numbering

I understand the lettering; that As are direct quotations and Bs are references or comments or paraphrases in regard to certain philosophers.

What I don't get is how to distinguish the Bs?! (pun not intended)

Example:

Heracleitus B50 - 'Listening not to me, but to the logos, it is wise to agree that
all things are one.'
(Hippolytus, Refutation of All Heresies 9.9.1)

... this is paraphrasing; Hippolytus is saying that Heracleitus SAID this.

While this...

Heracleitus - B70 '[Heraclitus judged human opinions to be] children’s
playthings.
(Stobaeus, Selections 2.1.16)

...this is quite clearly referencing; Stobaeus is talking ABOUT Heracleitus.

Those examples are obvious, the former is a famous reflection of Heracleitus, the latter explicitly refers to Heracleitus, so no issues in understanding these.

However, these are the exceptions. To the laymen, like myself, for most entries I can't tell the difference; if the entries are paraphrases or comments. Is Stobaeus saying that Heracleitus said this, or is he saying that Heracleitus was this?

Am I misunderstanding something here, or that just the way it is and something to contend with?

Thanks for getting to the end.