Way back in the BODs, bad old days, most aircraft cruised a fair bit faster than LRC and to decellerate to LRC gave a considerable gain in arrival fuel, although a longer sector time.
LRC is faster than MaxRC and was artificially set at 99%MRC, ECON is in the middle somewhere.
These days aircraft ECON speeds are a little slower that LRC and thus more fuel efficient.
Regards,
BH.