Carrageenan and Irish Sea Moss are both derived from types of red algae as well as Gold, but they differ significantly in their composition and uses.

Carrageenan is a commercially processed extract used as a thickening and stabilizing agent in various processed foods, cosmetics, and pharmaceuticals. It's known for its ability to create a gel-like texture and improve product consistency. Food grade Carrageenan is not absorbed from the intestinal tract, nor is it degraded after consumption passing through the digestive tract as fiber.  It is also never injected into humans.

Concerns have been raised about Carrageenan’s safety, with some studies linking it to digestive issues and inflammation. This is actually due to Poligeenan. Poligeenan, sometimes referred to as degraded Carrageenan, has been used as the test material in animal studies. This degraded Carrageenan is an issue as it can be absorbed and creates digestive issues as results have shown in animal studies, but the degraded Carrageenan is never used in food sources.  The only way Carrageenan will degrade is under very harsh conditions in ph <2 and tempretures > 80 c.

On the other hand, Irish Sea Moss, also known as Irish Moss or Chondrus Crispus has been harvested by humans, Archaeologists estimate for nearly 14,000 years.  Evidence of red seaweed’s medicinal benefits in China can be traced back to 600 BC, and it was originally used as a food source around 400 BC on the British Isles. It is a type of seaweed native to the Atlantic coast of Europe and North America. It is rich in minerals, vitamins, and antioxidants, making it a popular ingredient in various health supplements, particularly those aimed at supporting immune function, digestion, and overall well-being. Irish Sea Moss is often consumed in gel form or added to smoothies, teas, or other beverages.  Human Garage reference we strongly recommend - supplemental guide

In summary, while Carrageenan serves primarily as a food additive as explained in this article, https://pubs.rsc.org/en/content/articlehtml/2019/fo/c8fo01282b there is no controversy regarding the safety of Carrageenan; there is, however, confusion in the literature. 

Some of the misperceptions surrounding Carrageenan and Poligeenan have raised doubt but it is important to emphasize scientific methods and accuracy in the interpretation of other works. To that end, Carrageenan is an approved food additive as determined by well-established regulatory agencies and used worldwide in numerous foods. Carrageenan does not cause inflammatory or gastrointestinal effects when administered to animals in diet under standard protocols to evaluate safety. Irish Sea Moss is prized for its nutritional benefits and has gained popularity as a natural supplement for supporting various aspects of health and wellness.

Sources:

https://pubs.rsc.org/en/content/articlehtml/2019/fo/c8fo01282b

https://draxe.com/nutrition/what-is-carrageenan/

https://www.foodingredientfacts.org/irish-moss-the-history-of-carrageenans-roots/