How are Java edition and cross-play servers different?

Cross-play servers can be used by users of bedrock editions, in addition to being compatible with Windows, Mac, Linux, and Windows PCs.

Can Minecraft Java edition and Minecraft berock edition users co-exist?

Absolutely! By using a true cross platform Minecraft server, like the ones above, Minecraft Java players and Minecraft bedrock players can connect to the same world and game together - In most cases you won't even have to run the same version, as most servers use the ViaVersion plugin. You will need a unique IP address for each client to join the server. However, both are available in the server pages.

I use a Nintendo switch. MINECRAFT-CRAFTING Can I join the same Minecraft World as my friends using xBox?

Yes! You don't even need a Cross-Play servers to do that. All game consoles have the same game platform, Minecraft Bedrock Edition. You can invite your friends or other console players to play on any Bedrock servers.

Can Minecraft Realms be Cross-Platform?

Unfortunately, No. A Realm is an Mojang-hosted, small server that can only been joined by a few close friends via an invite code on Minecraft Bedrock Edition. Because Realms are hosted by Mojang, intalling the GeyserMC proxy (Which is what allows other players to join) is not possible.