Rye vs dark rye for starter

Both of those are dark rye flour.  Dark rye flour and whole rye flour are synonymous.  All it means is that none of the bran or germ has been removed in the milling process.  I have used both of these flours you have pictured and if my memory serves me the Hodgeson Mill is a little bit courser of a grind which is why it seems to have "darker flakes" to you.  That being said I have also seen dark rye flour that is fine ground where the entire flour has a darker hue.

If you think that you are going to achieve the "dark rye" color you see in a marble rye bread that you see at the store by using this dark rye flour I am going to have to burst you bubble.  The majority of dark rye breads that are found commercially use caramel color to achieve that coloration.  Alternatively some smaller bakeries have other ways in which they achieve the dark rye color including strong coffee, cocoa powder, molasses, and dark malt extract to name a few.  The original dark rye coloration, however, was achieved through extremely long bake times at low or receding temperatures that caused the maillard reaction to penetrate the through the entire loaf.  I believe the original practice was to put the rye bread in the wood fired oven at the end of the day after the oven had spent most of it heat and then remove it the next morning before re-firing the oven.  This would allow the loaves to bake for 10-14 hours at low temp.

It's the same whole rye flour.  BRM looks lighter because of the significantly finer grind.

Whole Grain.  That is what tells you the whole berry of rye is there, nothing removed,  but one is just a finer grind 

Despite what millers and marketers write on the label, there are three grades of rye flour.

• Light rye otherwise known as 100% rye flour, is ground from the middle endosperm (white flour) only.  It contains no germ or bran so consequently is higher in calories and lower in fibre and minerals.  This is what's largely used in supermarket and so called artisan ryes which aren't really ryes anyway because they are mostly wheat flour with rye added for flavour.  Just check the label.  Pure rye doughs are also harder to handle.
• Dark rye flour contains the endosperm plus the germ and part of the bran.  This is what's used in the traditional Schwarzbrot (black bread) or Bauernbrot (farmer's bread) of German speaking regions.
• Whole meal rye flour of course contains the whole rye berry.  It is used only for speciality breads such as pumpernickel.

My mother grew up on an alpine farm in Austria.  Rye was the only grain that could be grown at that altitude.  Bauernbrot was a staple for centuries.  During WWII, it was mandated that only whole grain flour could be milled.  Despite having grown up of rye bread, Mum found whole meal rye indigestible.  Her mother had to bake a little wheat flour bread just for her during that period.

I was sourcing dark rye from health food stores but have since found it much cheaper from "Simply No Knead".  I've tried an "organic" rye but that proved to be light rye which was disappointing in both taste and texture.  I've been disappointed in not being able to consistently buy anything approaching my grandmother's Bauernbrot so I've resorted to baking it myself.