They are both attempts to calculate a rating of how well a player is doing, but both fall short due to a lack of information in the available public player data and also by taking all battles into account including the early ones where most players will still be learning the game.
For the original efficiency rating which was first, I believe, used on Wot-News.de, the calculation is as follows:
Rating = $avgDamage * (1.5 / $avgTankTier + 0.2)
+ $avgFrags * (350 - 20 * $avgTankTier)
+ $avgSpotted * 200
+ 150 * ($avgCapture + $avgDefense);
so $avgDamage, for instance, is the average damage (total damage / number of battles), and $avgTankTier is the average tank tier (average based on battles, not number of tanks).
This the same rating that XVM has used for some time. Last week the rating was changed to this:
Rating = $avgDamage * (10 / ($avgTankTier + 2)) * (0.23 + 2 * $avgTankTier / 100)
+ $avgFrags * 250
+ $avgSpotted * 150
+ (log($avgCapture + 1,1.732)) * 150
+ $avgDefense * 150;
Capture points now have a lower effect on the rating, so players will find their ratings drop if they spent many games capturing bases rather than damaging/killing tanks.
The WN6 rating is an attempt to correlate rating with win rate, and the calculation is as follows:
RatingWN6 = ((1240 - 1040/ pow(min($avgTankTier,6),0.164)) * $avgFrags )
+ ($avgDamage * 530/(184 * pow(M_E, 0.24 * $avgTankTier) + 130))
+ ($avgSpotted * 125)
+ (max($avgDefense,2.2) * 100)
+ (((185 / (0.17 + pow(M_E,($winRate-35) * -0.134))) - 500) * 0.45)
+ ((6 - min($avgTankTier,6)) * -60);
where $winRate = 100 * $wins / $battles (so win rate as a percentage).
You can read more about WN6 (and it's previous incarnations) at
http://forum.worldoftanks.com/index.php ... __st__1080 , looks for posts from Praetor77 as he developed the calculation. It's supposed to be less "vulnerable" to players using low tier tanks and spend most of their time capping bases, although the new XVM/WoT-New rating claims the same thing.
It looks like 1stcav.net are still using the old XVM rating (I wrote the code that the 1stcav.net sig uses, the author hasn't released a new version with the new rating calc in yet but I've amended it in mine) as your sig is showing 948 which is the old value.
Don't take them seriously! I have found myself though that aiming to get above 1000 has improved my game - I use WoT Statistics (
http://www.saais.co.za/ ) to look at results straight after a battle on my PC, and also WoT Performance Analyzer (
http://www.vbaddict.net/wot.php) to get more detailed information on each game. I also used these for the handy tools such as seeing which tanks I have left to kill to get each medal for killing all tanks of a particular country - I've only got 3 German tanks left to kill (E50M, Maus, GW Typ E) and a few US and French tanks for their medals.
Also check out Noobmeter (
http://www.noobmeter.com) as this gives you all the rating figures plus it's own, and you can get it to show the ratings for last 7 days, last 1000 battles, and last 30 days once it has enough data which is a better representation of how you are playing. Even my own simple stats page at
wot/stats.php shows that your ratings for the past 747 battles (which is how long it's been tracking your data, and will do a better job if you use my signature generator instead of the one at 1stcav.net as mine will track changes daily) are all around 200-300 points higher than your overall ratings.