When you add a channel you add it to your Roku account. Any Roku device linked to that account will get that channel. Add/delete on one, add/delete on all.
The only way to have different channel lists is to link to different Roku accounts. Any subscriptions taken out directly with the channel on the channels website will be viewable on all devices via the channel's Roku app. But any subscriptions taken out through Roku will be attached to the linked Roku account and so can only be viewed on Rokus attached to that account.
Roku Streaming Stick +, 3810X, Ser YH0059427035, wifi - Samsung UN55ES6100
Roku Streaming Stick, 3600X, Ser 5S56D8240827, wifi - JVC EM37T