It's better by one. Just like a guitar amp is better if the dial goes to 11 instead of 10.
Seriously though, are you asking for the differences in the standard or are you asking how the manufacturers attain the higher efficiency?
"Dear future generations: Please accept our apologies. We were rolling drunk on petroleum."
— Kilgore Trout (via Kurt Vonnegut)
For the best use of Eng-Tips, please click here -> faq731-376
As probably you now, according to IEC 60034-30:2009 the motor efficiency was stated as IE1[STANDARD] IE2[HIGH efficiency] IE3 [Premium Efficiency].
The old standard EN 60034-2:1996 was two: EFF2 standard efficiency and EFF1 high efficiency.
IEC 60034-30:2009 states new symbols for EFF1 and EFF2 as you could see in the following article:
EFF2 standard efficiency>>> IE1
EFF1 high efficiency becomes IE2
IE3 is a new classification for premium efficiency
The reason is the reduced energy consume [2-8% less than standard in IE3-premium efficiency].This is the new international
policy in order to reduce pollution and earth heating produced by power plants[Global Warming Policy].
The same policy which requires high lighting efficiency bulb and so on.