Help!/About the previously-unpublished Doctor Whoah! strips

From Tardis Wiki, the free Doctor Who reference

Some of these strips are earlier versions of strips that were ultimately published.

Doctor What 4 and another unpublished strip I haven’t covered yet are both earlier versions of Doctor Whoah! 376. The final strip is changed just enough to be considered its own strip, but the two prototypes are nearly identical save for a couple minor added details.

Furthermore, Doctor What 6 is an early version of Doctor Whoah! 415, with the only difference being that the final strip was completely redrawn.

What I want to know is: what differences between the these strips be enough to constitute their own pages?