Assembly language: Ampersand before a register
From the instruction set provided in the link it is evident that 

sbbo &amp;r2, r1, 5, 8


is the only supported in clpru assembler. But in pasm

sbbo r2, r1, 5, 8


is also supported. So, in pasm they are same. But if clpru was used only the first syntax would work.