What is the difference between fibrinogen (fibrin) and platelets?
Together they participate in forming a hemostatic clot.
Fibrinogen and fibrin are not the same thing.
Fibrinogen is a protein found in blood plasma. It converts to fibrin, under the influence of thrombin
Fibrin that is formed from fibrinogen is a non-globular protein involved in the clotting of blood. Fibrin is stabilized by an enzyme called factor XIII that crosslinks fibrin.
Here you can see the whole process from fibrinogen to a crosslinked fibrin mesh.
Platelets are components of blood which participate in blood clotting.Their function is to stop bleeding.
Here is a really good animation of the team work between fibrin and platelets.