There is a difference in a Russian Boar, and a feral hog genetically, however feral pigs often interbreed with wild boar, producing descendants similar in appearance to wild boar; these can then be difficult to distinguish from natural or introduced true wild boar.
Yes, sort of like there being a genetic difference between German and western Russian people. There is a genetic difference, but it is extremely small. They are the same species. Domestic hogs have the genetic code for "Russian boars." How is that possible? Simple. European domestic hogs are domesticated from European wild boar, AKA Russian boar.
There are no morphological traits that are deterministic of a hog being a "Russian boar" that can be applied with any level of certainty short of craniometrics and you can't do those on a hog with skin.
Hogs are a very plastic species and vary considerably throughout their population. Hair type and color, tail curl, leg length, body shape, shield development, and euro-teeth are all used, but without any actual science behind them. It is a form of folk taxonomy.
When domestics return to the wild, it doesn't take too many generations for the offspring to resemble the primal stock which looks a lot like wild Russian boar. How ironic. It isn't because they have been breeding with Russian boars.
As far as penetration is concerned between the 2, on males there is a "shield" that is basically scar tissue and cartilage that has built up over time from rubbing and fighting.
I am sorry Freedom Fighter, but the shield is not scar tissue built up from rubbing and fighting. I have watched hogs fight and most of their damage to their opponents is on the chest area where the shield isn't present via upwards thrusts with their tusks. Back in February, you even noted that you never thought it was scar tissue, LOL. If the shield was scar tissue, then the hogs would have scarring all over the shoulders and upper outsides of their backs and generally they don't. I have shot hogs with some thick shields and found their bodies relatively undamaged by what would have to have been extensive fighting to get that much scarring only under the skin, but how it was that they weren't scarred on the exterior of the skin was a problem. They aren't getting shield from rubbing either or they would have shield butts.
http://www.thehighroad.org/showthread.php?t=572323&highlight=hog+shield+scar+callus
The traits that people often attribute to being a wild boar or Russian boar are traits that are not necessarily indicative of being wild or Russian. People are very selective in using the traits to identify their kills as being Russian, I have noticed. Most of the people who will tell you about Russian hogs don't even realize they are the same species as our domestic hogs or that domestic hogs came from wild hogs. They have the same geno type (genetic code), but differ in phenotype (expression of genetic code such as visible traits).
Heck, some folks even make up traits...
Check out the Euro-tooth in the following link. It is claimed that this took indicates that the hog is a hybrid between a domestic and a wild hog.
http://www.texasboars.com/articles/aging.html
http://www.hunting-in-texas.com/learnhogs.htm
Chances are that if you shoot an adult hog and the tooth isn't broken off, it will have this tooth. So you much be shooting a hydrid wild/domestic hog, right? You are just shooting some feral hog, but one with real Russian blood. LOL, the claim is totally bogus.
The tooth is present most of the time and is part of the normal dental arcade of the hogs. Like our wisdom teeth, however, the tooth is being lost over time. It is considered a vestigial tooth. See post 27 here...
http://www.thehighroad.org/showthread.php?t=450614&page=2&highlight=euro+tooth
Without doing the craniometrics or actual genetic testing, anyone's claims are a hog being more or less "Russian" are as valid an anyone else' claims that it isn't. Funny thing is that you get a lot of people identifying "Russian" hogs who have never actually handled one. The hog I killed can't be claimed to be any more "Russian" than the hog you killed if we are basing our assessments on external visible traits. There is no known correllation between trait frequency or distribution on the body to indicate the level of Russianess" but many hunters will have you believe that there is.
However, if somebody has found any new information to indicate otherwise, I would love to see the study.