From what I remember driving them is that the M-Sport and Sportline are the same in seat design - if that's what you are asking.
Cosmetically if you get M-Sport, the seats are either black leather seats ( LCSW ) or Coral Red ( LCL5 ). You can't get the black seats with red piping ( LCL3 ) in M-Sport. You can only get that in Sport.
Current: F30 - 335i AT M-Sport MPPK
Previous: E90 - 335xi MT, E90 - 330i MT, E46 - 330i MT