SFLRCDNBR() is a keyword used on a field in a subfile control record format. It mostly tells the system which page of the subfile to display first.
DSPATR(PC) is a keyword used on a field in a record format to tell the system where the cursor should be when the record is displayed.
SFLRCDNBR() is about pages in a subfile. DSPATR(PC) is about fields on the display.
The descriptions are in the display file DDS manual. More details are in the manual then would be in an answer here.