I see the similarities, even if they're superficial. They're both giving publishers the ability to monetize their followers by selling access to additional premium content.
They are not similar at all besides both being called a "subscription". Facebook subscriptions are giving users access to content they cannot get without, and there are different price points. YouTube is offering a Twitch style $5 a month "patronage" like subscription. The videos will not be locked down to paying people only.
It sounds like some of the content may be locked down, but whether or not the extra content is any good will vary from channel to channel.
> It will also allow subscribers to gain access to members-only posts in the Community tab where creators will share custom perks from time to time, like access to an exclusive live stream, additional videos, shout-outs, news of upcoming events, early access to ticket sales and other things.