I'll give it a go.
'Max range cruise' : Is flying at the speed at which maximum distance is covered with a given fuel quantity. At a given weight and altitude, a max specific range can be found and the corresponding speed or Mach number is then the Max Range Cruise speed. Note that as the weight decreases so does the max range speed. You might also experience speed instability.
'Long range cruise' : At this speed the specific range corresponds to 99% of max range cruise. However, the 1% loss is mostly compensated for by the higher cruise speed. Speed stability is also higher. As for max range the speed also decreases with weight.
Pheeww, I need a beer now.