1. Different chemical structures:
Organosilicon: Organosilicon, also known as organosilicon compounds, refers to compounds containing Si-C bonds and at least one organic group directly connected to silicon atoms. Compounds that connect organic groups to silicon atoms through oxygen, sulfur, nitrogen, etc. are also commonly referred to as organosilicon compounds. Polysiloxane is one of the most common types, with silicon oxygen bonds (- Si-O-Si -) as the backbone, accounting for over 90% of the total amount of organic silicon compounds. A. The abundant methyl groups on Si atoms shield the high-energy polysiloxane backbone; B. C-H is non-polar, resulting in very weak intermolecular interactions; C. The Si-O bond length is longer and the Si-O-Si bond angle is larger; D. Si-O bonds are covalent bonds with 50% ionic bond characteristics (covalent bonds have directionality, ionic bonds have no directionality).
Organic silicone resin: It is a highly cross-linked network structure of polydimethylsiloxane, usually containing hydroxyl groups. Its structure not only contains organic groups, but also has the characteristics of inorganic materials.

Room termperature curing polysilazane, pls check IOTA 9150, IOTA 9150A. 
High termperature curing polysilazane, pls check IOTA 9108, IOTA 9118.