Rails Environment VS Deploy Environment
When the same verbiage is used in multiple contexts, it can be uber confusing for new people. On my team, I recall over the years that the majority of people getting started with us get caught up briefly on the difference between the Rails Environments concept, vs our concept of deploying to multiple environments (like dev, staging, prod, etc).
For people brand new to the industry, the idea of multiple deployment environments may be the new part.