Structural aspects:

　　Both heparinoid and heparin are polysaccharide substances with relatively complex chemical structures. Their basic skeletons are composed of sugar units. For example, they both contain common sugar components like glucosamine, and these sugar units are connected to each other through specific chemical bonds to form large polysaccharide structures.

　　Sulfation modifications exist in both of them. Sulfate groups play a crucial role in their physiological functions and enable them to interact better with other biomolecules in the body.

　　Pharmacological effects:

　　The main similarity lies in their anticoagulant activities. They are both able to interfere with the blood clotting cascade in the human body by interacting with antithrombin and other key factors in the clotting process. This helps in inhibiting the activation of certain clotting factors and thus plays an important role in preventing blood clot formation. They are widely used in clinical settings for the prophylaxis and treatment of thrombotic disorders such as deep vein thrombosis and pulmonary embolism.

　　Differences between Heparinoid and Heparin

　　Structural differences:

　　Although they have similar basic sugar backbones, there are variations in the detailed arrangements of sugar units and side chains. Heparinoids may have different patterns of sugar linkages or additional unique sugar residues compared to heparin. For example, the degree of sulfation might differ between them, with some heparinoids having a modified or less extensive sulfation pattern on their sugar backbones, which can lead to differences in their biological activities.

　　The molecular weight distribution can also vary. Heparin usually has a relatively narrow range of molecular weights in its typical pharmaceutical preparations, while heparinoids may have a broader or different distribution of molecular weights depending on their specific sources or synthetic modifications.

　　Pharmacological and clinical differences:

　　In terms of anticoagulant potency, while both are effective anticoagulants, the specific strength of their anticoagulant effects can vary. Some heparinoids may have a more moderate or targeted anticoagulant action compared to heparin, which might make them suitable for certain patient populations who cannot tolerate the stronger anticoagulant effect of heparin or are at a different level of risk for thrombosis.

　　Heparinoids often have additional biological properties that heparin may not possess or may have to a lesser extent. For instance, some heparinoids show more pronounced anti-inflammatory properties and can play a role in modulating cell signaling pathways related to tissue repair and wound healing. This makes heparinoids potentially useful in different clinical scenarios such as dermatological applications for treating skin ulcers or burns, where improving local blood circulation and promoting tissue repair are important aspects, which is not the primary focus of heparin's clinical use.

　　Regarding adverse reactions, heparin is known to have a risk of causing heparin-induced thrombocytopenia (HIT) in some patients, which is an immune-mediated adverse reaction. Some heparinoids, on the other hand, have been developed or selected for use in patients who are at a higher risk of developing HIT with heparin, as they may have a lower tendency to trigger such an adverse reaction due to their different structural and immunological characteristics.