Time for my RWBY Fandom pet peeve:
'The Maya engine.'
Autodesk Maya isn't an engine in the sense that we know from games development. It's 3d visual effects, animation and modelling software, which is quite different.
What 'engine' can refer to in RWBY's pipeline is the middleware plugin renderer used during their rendering output stage, and this is done (at least as of 2018) in both Maya (for backgrounds) and Autodesk 3ds Max (for the stylized toon shading and block outline we see on characters). Plugin render engine's are chosen based on what meet their visual requirements.
Examples of rendering engines:
Arnold - pre-loaded Maya & Max default
V-Ray - Standard alternative to Arnold for Maya & Max
Redshift - GPU-based renderer
Pencil+ - 3ds Max-based shader & rendering engine, this is what RWBY uses for its toon shading.
There is also Maya's cmd engine (Max also uses one respectively) that can be used for scripting certain tools and auto-solutions, but I won't get into that.
Source: Degree in 3d Animation & Games Developer since 2017