Honda automobile Type R models are special performance editions of their respective model families.
The design of Type R models was originally focused on race conditions, with an emphasis on minimizing weight, and maximizing performance potential (e.g. engine tuning, suspension set-up). Thus, Type R models were first conceived for racetracks. However, due to Honda's increased focus on their highly regarded VTEC engines, the Type R was eventually designed for a much wider market.
Go search more on wiki about the R.
Basically, R is race edition and si is standard one or basic street type car. You will def able to buy plenty of Si and R spare parts in UAE market even if you are importing car from outside. But Honda dealer might act little bit upset while fixing your imported car (rem that).