In PK51 C compiler, do exist the debug mode & release mode likely IAR compiler?
Yes. I think there is no debug/release mode in KEIL. In the debug mode, debugger use .obj files, and generate hex file in the state of release mode.
uVision always creates obj files; There is an option on the output tab to create a hex file in addition So you don't need to choose between Debug and Release - you get all the files all the time! (the time taken to generate the hex from the executable is negligible).