I would hazard to say, one is generate by amino propyl silane and the other is generate by amino propyl tri-ethoxy silane. The former could be a chloro-silane. The end result in film structure depends critically both on the type of silane (APS versus APTES) as well as on the method (wet chemistry versus vapor deposition) and the care used in the entire silynation process.

thank you sir

One approach utilizes 3-aminopropyl-trietoxy silane (APTES), enabling one to obtain a smooth surface termed AP-mica. This surface binds nucleic acids and nucleoprotein complexes in a wide range of ionic strengths, in the absence of divalent cations and in a broad range of pH. Another method utilizes aminopropyl silatrane (APS) to yield an APS-mica surface. The advantage of APS-mica compared with AP-mica is the ability to obtain reliable and reproducible time-lapse images in aqueous solutions