No, what Dane says isn't entirely correct. IMO, I'd sort them like this:
...
One has to keep in mind the following:
After the release of WFA Relic focus on fixing the performance of mainline infantry one vs the other.
In order to achieve that the come up with 2 principle "weapon profiles curves" and "relative positioning".
Weapon profiles curves meant that weapon of the same type should have similar curves and perform better in certain ranges.
That would allow for player to easily know what range is optimum for their Squad. It would also allow to maximize the advantage when fighting against unit with other "weapon profile".
That help with the concept of "relative positioning" where a player would in a get more out of his unit if he was able to force a engagement to take place in certain ranges.
Things become more complicated for weapon upgrades (and doctrinal units) since they would had to be worth investing so some weapon do not follow "weapon profile curves".
To make thing even worse some of the latest patches seem to be moving away from this 2 principle and seem to be using linear weapon profiles.
My main point here is that (up until some latest patches anyway) many default weapon follow "weapon profiles curves" while many weapon upgrades (or doctrinal infantry) are more "exotic".
This is actually a shame since the 2 principles where a huge improvement and patch should look for solution with in these parameters (and solution exist) instead creating weapons with unique/on typical performance.