there are Verterans' agencies and veterans' organizations. they are not the same thing and they don't all count the same way. the VA, for example, may be including more categories of "injury" than the military does. they also have a more accurate picture of service-connected health issues that don't surface until after someone has left the military.
my former spouse served his last tour of combat duty in the 70s. he retired from the Army in seemingly good health. 2 years ago, he died of a cancer the VA determined was related to Agent Orange. More than 30 years passed between the combat and his service-connected death. his case was not unique.
many soldiers, sailors, airmen, and marines come back from combat seeming to be just fine and dandy. unfortunately, the horrors of combat, the stress of being away from home and family and - believe it or not - the stress related to homecoming and reunion with family and friends can scar a person in ways they aren't aware of. it may not come out in the open until years later.
a soldier might get sick and have to return home, but not necessarily have been injured in the classic sense. then there are degrees of injury; whether or not the damage is permanent and disabling; etc, etc, etc. a soldier may have become ill or have been injured during a time of war, but not actually in a combat zone. there are many more possible reasons for differences in counts.
finally, and unfortunately, not all veterans' organizations are "created equal". they aren't all formed for the same reasons; they don't all have the same goals and agendas.
i work in the military culture. as proud as i am of that, i don't doubt that some things are under-reported or swept under the rug. i have seen soldiers well served and i've seen soldiers treated unfairly. it shouldn't happen. it does happen. but not to the degree that the more angry and aggresive - and sometimes generally anti-military - activists would have us believe.
bottom line never changes ... don't believe everything you hear. the truth is out there ... it's just really hard to find.
pray for them. do what you can for them. and please - whenever you see someone you know is serving our country, walk up and say "thank you". they never ask for it; they never expect it; and they never forget it.