Hi! I don't understand the difference between Arduino UNO R3 and Arduino UNO SMD R3 cards. 
Can someone help me please !!!!
I should choose one of them to buy.
Thanks.
As their names state, the Uno SMD has a SMD microcontroler while the UNO R3 (the "normal" one) has a DIP version of the microcontroleur. I don't think there is any other difference.
Go for the Arduino UNO R3, the one with the DIP MCU. If you fry the MCU, you'll be able to replace it easily.
Thank you for your help 
If you fry the MCU, you'll be able to replace it easily.
And if you fry the USB/Serial chip, you're hosed either way.
I didn't say that everything was safe 
The Uno R3 has the Atmega processor in a DIP package in a socket - this has the advantage that you can remove it, replace it, etc.
The SMD version has the processor in SMD package, not socketed. They're slightly cheaper. While the SMD version of the chip has 2 extra pins, those aren't made available on the Uno SMD, sadly (I think in the name of making the two boards equivalent)
So yeah, I think the R3 is the better purchase - as stated in the description for the SMD one, it was motivated by a shortage of DIP packaged ATmega328's (there have historically been shortages of these, to the point where one of the major hobby vendors got a batch of fakes)
I think that i will buy Arduino UNO R3.
My project is: Make a home security system with sensors for intrusion detection and a GSM shield for notificaion. The project can be expanded using RFID reader, thermal printer, 433 Mhz mdoules, internet connectivity etc.
Does there other suitable cards for this topic? I need an advice ,please, before buying !!
How can i detect counterfeiting !!!!
How can i detect counterfeiting !!!!
Buy from a reputable dealer, or Arduino directly.
Most boards purchased via e-bay for example are either clones and clearly identified as such ("arduino compatible"),
or are counterfeits that claim to be genuine Articles.
Damn, I recently bought a kit that came with a MAKE Special Edition SMD. The box didn't indicate which came inside. I'm a newbie so I think I may have to buy the DIP and have my Special Edition hanging around for the future.
Make your own arduino for 8 dollars. Google Hackduino