These 2 buttons do not do the same thing. The X indicates which differential will be locked when pressed.
Centre Differential Lock Button: More info can be found here.
Rear Differential Lock Button: More info can be found here.
About Mick Farmer
For the last 25+ years, I have been the lead trainer /director for OnCourse. Have played a leading role in developing their courses into, probably, the best off road training courses, globally.