Even sellers of various materials incorrectly use these words in describing their products. I'll try to clarify. Silicon is the name of the element. All of the above contain silicon but in different forms. Silicon-Bronze is a proper use of this term because the element silicon is mixed with copper to form the alloy.
Silicones are carbon compounds that have a silicon atom bonded to an oxygen by a double bond.
These compounds are used in rubbers, paints, oils etc. Silicone rubber moulding material is a proper use of the term as is silicone breast enhancement. Silica is a name for silicon dioxide, commonly seen as sand. Silica flour is very fine ground-up sand. Silicates are Silicon sompounds at least one element other than silicon and oxygen.