Are they two different names to describe the same thing?
Coordicide refers to a goal on the IOTA roadmap, namely to remove the coordinator and create a network that works safely and reliably without it.
Pollen is the codename for the first phase of coordicide, which refers to creating a network for testing a promising coordicide strategy which will hopefully be used later. The later phases are called Nectar and Honey.
The naming was changed yesterday to IOTA 2.0 DevNet (Development Network). Please read this blog post: https://blog.iota.org/path-towards-full-decentralization-with-iota-2-0/