I am rehashing this topic for a friend of mine who wanted a more definitive answer on how to determine Black Pastels versus Cinnamons.
I realize that it can be tough now a days with everyone and their mother posting up pictures of things and advertising.
This is not the best way to learn about specific morphs, but that's alright.
You came to the right place!
Let's begin, shall we?
Cinnamons are more common than Black Pastels, but not by much. Black Pastels came a tad bit later than the Cinnies to the morph game. They, like the Butters, were actually worth more back in the day, although now that is debatable.
I still think Black Pastels are harder to come by than Cinnamons, but that is also because I am not really looking for them and honestly am not really paying attention much to that particular sector of the market.
Yes, they are compatible, but they, again like the Butters and the Lessers, are visually and distinctively different.
Cinnamons are notably more reddish in tone than the Black Pastels. They have brighter notes of brown, and brighter notes of color in general. (Ergo the name Cinnamon, reddish brown)
They have squiggly patterns, with somewhat odd shaped alien heads that can actually continue down the body of the animal. (As you can see above, I am talking about the tail pattern below the striped portion of this particular animal)
The head coloration compared to normals and the like is different. The head color is brown all over, a chocolate color, if you will.
Good quality Cinnamons have significant blushing on the sides, which will grow into light reddish brown tones later in life.
Note the pattern on this baby. Melted alien heads, high blushing, a dark overall color, and a dark similar head color.
Black Pastels are much darker. They tend toward dark chocolate rather than a cinnamon tone, and do not have as much blushing that is inherent in Cinnamons. Their patterns are even more "wonky" than that of the Cinnamons, with what I like to call the "extra". As you can see in the female below, there are dark black speckles within the alien heads of the pattern. This is a clear indicator of a Black Pastel, although this is also a marker of a Het Red. Other than the speckles, the type of patterning is similar to that of the Cinnamons.
Note the color difference.
This female below is also a Black Pastel, but bred into a lighter animal, thus producing a more complicated Black Pastel coloration. She is absolutely a Black Pastel, as indicated within her pattern (note the squiggles), but her color is much lighter than that of typical Black Pastels.
This was done on purpose for a breeding project, and will be used for lighter projects in the future.
She does have more blushing, and a lighter gold tone.
The difference between a light Cinnamon and a light Black Pastel is that Black Pastels turn gold, where Cinnamons, when lightened up with breedings, turn red.
It can be complicated, but know that it can be easily solved once you learn what to look for.
Just keep looking.
Hope this helps, and have a great day, my friends!