Thanks! The red and ocher one looks very similar to what I use, so if I had to buy sand, for covering the ground, I'd go for that. The grey-black one looks more like pebbles, I would not use that. So there is not only a different color, but they are really a different texture.
For comparison, how the sand looks that I use (not only color but also texture), see the attached images. In the left image, there is only sand (on the ground), a large stone and in the background a fake stone structure.
For shaping something, I'd really stick with the excavator clay. In the second image, you see that ceiling of the cave, towards the left? Half of it (upper half in the image) is fake stone, but lower half is then the excavator clay. This structure holds up for already almost 2 years!
Both together, some sand plus excavator clay, IMHO work really well and if I had to design a second bearded dragon enclosure, I would repeat that for sure.
If covering the ground with sand, I recommend: Especially the first weeks, spraying it with water each day in the morning. It then dries out and forms a quite hard surface (if I want to replace some sand, I really have to break the crust apart using a metal spoon or shovel; think of it like soil or sand hardening in nature). From then on, spraying regularly isn't that important anymore. I do it on most days to mimic morning dew, but if for any reason it is not sprayed (e.g.: both me and my partner are away and I don't want to bother somebody who takes care with doing also that), nothing bad happens. With that, I also have no problems with dusty sand flying around. However, some (or just one?) user here reported having found dust from the sand covering the lamps over time (I do not have this problem, but it might depend on the type of sand and the distance of the lamps from the sand). For this reason, when switching to large amounts of sand, I recommend checking that, and if necessary cleaning off the lamps regularly.
