The difference is the black plastic will eventually split center to edge ruining your film. It is also much harder to put on.
For best results, drop the loaded reel in the full tank of developer rather than pour in. Then the stainless cap is added with one motion with the other hand. I have Nikor tanks for 50 years and just bought a new one for "just in case." Some cheap Japanese copies were made, but they did not use 316 stainless and were prone to rust.
The rest pale in functionality and durability, but they all work if you learn the quirks.