Arduino uno r3 is the new rees52 uno r3. In addition to all the features of the previous board, the uno now uses an ch340g instead of the 8u2 found on the uno (or the ftdi found on previous generations).This allows for faster transfer rates and more memory.
This is the new rees52 uno r3
This allows for faster transfer rates and more memory
E popular development boards arduino uno with smd processor and the converter ch340