What is the difference between 'Instance' and 'Community'?

I might be talking bullshit here as I'm also pretty new to this. But I believe an instance is the server (basically like Reddit) where all the communities (Subreddits) are located. These instances can federate with other instances to grow in a decentralized fashion. Every instance can impose site-wide rules (e.g. beehaw disabled the downvote button, I believe, so you can't downvote anyone in all of the communities that belong to the beehaw instance).

Someone please correct me if I'm wrong!

Yep! It's a bunch of reddits that all talk to each other, and each one can have whatever communities (subs) it wants.
Every instance can impose site-wide rules (e.g. beehaw disabled the downvote button, I believe, so you can’t downvote anyone in all of the communities that belong to the beehaw instance).

That’s true for those on beehaw. But if I look at a thread hosted on beehaw from another instance I can downvote. Since I’m looking at a copy/synced version of the thread and I don’t have downvotes disabled.

Still though. It limits the abuse of downvotes to an extent.

Here’s an example screenshot. Note the downvotes are there.

Example 2 from beehaw no downvote button
- Cool, thanks for the clarification! I'm still trying to get the hang of the FediVerse. I'm liking it very much so far!

communities are exactly like subreddits but instances are servers run by different individuals, think of them as small reddits but all able to talk to each other, that is why it is called federated

Oh, got ya! What about different links for lemmy? For example, the ones that end in .ee or .ml? Are those instances?
- Yup! Those websites are the instances which are the infrastructure and interface by which you can access communities - each of which is hosted on a specific instance. An instance is essentially the collection of all the communities it hosts and all of the users signed up through that instance.

The 'instance' is the 'server' that you made your account with.

Your 'instance' is 'lemmy.fmhy.ml'.

A community is essentially a subreddit. As far as I know, there isn't really an official term for it yet. I have been calling them 'sublemmys'.

sublemmy is probably not a great term, since it references lemmy rather than being a generic threadiverse term
- You're right but let's not confuse the OP
Why not just call it a community?
The official term IS community.

Simplified way to look at it:

Instance is like a server, it hosts your account and some communities.

Communities are like "subreddits". It has to created / operated on one of the instances, but is accessible to all federated instances (which is largely the norm).

An analogy is email. You can choose your email provider (Gmail, Protonmail, Fastmail etc) and you will have an unique email address based on that provider (e.g. someguy@gmail.com is different from someguy@fastmail.com), but you will have the ability to send emails to anyone (unless you are blocked).

Something to add: when looking at the Reddit analogy, there is a really key difference to understand. While reddit.com is somewhat equivalent to a lemmy instance (eg lemmy.world), it’s important to understand that, while there is only one reddit, there are many many lemmy instances.

This means that when you talk about a subreddit (called a community in lemmy), you automatically know that the subreddit is a community located on reddit.com. If you talk about r/memes, it goes without saying that you are talking about reddit.com/r/memes.

When you shift to lemmy world, if you just talk about /c/memes, that may not be enough info to know which /c/memes you’re referring too. Are you talking about lemmy.world/c/memes? Or lemm.ee/c/memes? Or one of the hundred or more other communities named memes on another Lemmy instance?

Ok… so you’ve created an account on an instance. I’ll use lemmy.world as an example because that is where this discussion is hosted. Your account info is stored on lemmy.world servers. You are subject to the rules and administration of lemmy.world. Your “local” feed consists of posts made on lemmy.world communities.

BUT lemmy.world is also “federated” with many other instances. Take a look. The list is huge: https://lemmy.world/instances . This means that if you are on lemmy.world and choose to browse “all”, you will see communities and posts not just on lemmy.world, but also communities and posts on other federated instances. You can also subscribe to those communities so that they show up on your “subscribed” (aka “home”) feed. Note that there are complexities here around which content you will see from federated instances. At a high level just know that you don’t automatically see all content from other instances… you should put a pin in that topic and learn more about it once you have the general layout down.

Lemmy.world is also “defederated” with some instances as well, which means that their content and users are blocked from lemmy.world.

Lots of good answers here, but I'd also like to add that you may come across "magazine" instead of "community". This is from Kbin which commonly federates with Lemmy. So m/ and c/ are similar but just different platforms in the fediverse.

Instances are where the communities are hosted. Think of them like several different reddits with the subs spread out among them

Simple explanation: imagine an instance as an apartment house, where communities are apartments (where people can gather). You also have neighbor buildings (instances) with their own apartments. You can go and visit them freely if you want. In that case, federation will be like a city I guess

It's the same difference as the one between Reddit = instance and a subreddit = community:

instance - a platform hosted somewhere. It has its own users, communities, admins.
community - it's a space for a topic inside an instance. It has local moderators, that must abide to the rules of the admins of that instance, and may set up their own rules.

The big difference here is that instances can communicate with each other. For example: you're a user of the instance lemmy.fmhy.ml, you're posting in a community from lemmy.world, and I'm replying to your post from lemmy.ml. There's nothing remotely similar in Reddit.

Instance of lemmy like lemmy.world, lemmy.ml or beehaw.org are the servers which host the software running lemmy. Communities are the hosted on those instances.

It's pretty obvious if you go through the docs.

its pretty obvious if you go through the docs

What a snarky way to end your comment. People don’t wanna do homework to browse a website

Simplified way to look at it:

Instance is like a server, it hosts your account and some communities.

Communities are like "subreddits". It has to created / operated on one of the instances, but is accessible to all federated instances (which is largely the norm).

An analogy is email. You can choose your email provider (Gmail, Protonmail, Fastmail etc) and you will have an unique email address based on that provider (e.g. someguy@gmail.com is different from someguy@fastmail.com), but you will have the ability to send emails to anyone (unless you are blocked).