I'm reading around Redis at the moment and trying to find a good understanding of what a 'node' is terms of how Redis works. Am I right to think of it in the same was as an endpoint?
In Redis' context, a node is a server running one or more redis-server processes.
Endpoint is a network address through which you can access one or more such processes, depending on how Redis is clustered.
When using the open source Redis cluster, an endpoint is any of the processes - meaning a node's address and the port that the process listens to. Redis client libraries use the protocol to interrogate the clustered redis-server process about other members of the cluster (again, processes listening on ports on nodes), so they can establish connections to other endpoints accordingly.
Disclaimer: it appears that you're asking about AWS ElastiCache, which may or may not be using the OSS implementation in whole or partially. I do not claim to have any knowledge on that subject.