The Mauler is described as very large, and usually being used as a beast of burden to carry equipment for the Chimera, but is able to shoot super-heated saliva, similar to Napalm. It can also cough up a pod which shoots out sticky tendril appendages. These tendrils can infect anything they touch.
Mauler, not Marauder
The above characteristics of the Mauler are remarkably similar to the Chimeran Marauder. However, in-game, the word "Marauder" is used, whereas the website describes a Mauler. Hence, unless there has been some sort of spelling error in the website, these two Chimera cannot possibly be the same creature.
In Resistance: The Gathering Storm, it is made clear that the Mauler is a separate strain of Chimera, and being describe as entirely different from Marauders. Considering how similar the Mauler and Marauder are, it's possible that the Marauder is a substrain of the Mauler that is used for combat purposes rather than labor.
Another possibility is that the Marauder evolved from and eventually replaced the Mauler, like with the Ravagers replacing the Brutes. This is quite likely, as the Marauders' abilities are more advanced versions of the Maulers' (they both share superheated saliva, albeit the Marauder's is more like the fire of a Titan's cannon, plus the tendrils of the pod it coughs up catches fire and does damage to victims). Since the Marauder is encountered a year after the events of Resistance: The Gathering Storm, and if we take into account the rapid evolution of the Ravager, this is probably the most likely scenario.