Prototype testing at a large scale requires a careful choice of words.
Let’s work backwards:
Implementation: contains the assumption that the set of concepts has been tested and proven and is worth committing to at full-scale.
Piloting: The set of concepts has been developed, tested in small parts, and is now ready to be tested at full scale.
Field Testing: The pieces are ready to be tested in context. Participants will use parts, some in combination, but the ideas are still being developed.
Prototype Testing: Each individual part will be developed, refined and used in small tests.
These are all terms that refer to testing ideas in context. There may be some usability testing, or other types of tests that happen before bringing the ideas into context.