What is the major difference between MV medium voltage and LV Low Voltage?

DIFFERENCE BETWEEN LOW VOLTAGE & MEDIUM VOLTAGE IS AS FOLLOWS

LOW VOLTAGE -3 CORE FOR LV MOTOR LOADS &4 CORE FOR OTHER EQUIPMENTS 

MEDIUM VOLTAGE -3 CORE FOR MV MOTOR LOADS & SECONDARY SUB STATIONS

The main difference is in the level of voltage and current, on low voltage we have big current and according to that big losses in cooper, on high voltage we have low current so we usually use high voltage when we want to transfer energy on high distance with low losses, because of this we uses transformer which increase or decrease voltage and current level.

Low Voltage is 1 volt AC Tto 1000V where as Medium Voltage is 1000 upto 44KV

Well, simple definition is: 

LV: Systems with voltages less than 11kV

MV: Systems with voltages between 11kV to 52kV

Medium Voltage has Voltage  13.8 KV

Low Voltage has Voltage Range from 220V to 480 V

uptoVlot is considered low voltage generation and or  for power distribution

but any voltage from more than volt uptokV is considered to be MV distribution or Transmission of power

Any  power  transmitted at a voltage  higher thankV uptoKV is considered a HV transmission  but any voltage  above  KV to   KV  used for power transmission is  considered as EHV transmission of Power