@manicdee no they are separate instances. mastodon.social is the giga mega server by @Gargron and #Mastodon devs. It's considered the default most used.

mstdn.social is a smaller (but still very very popular) #fedi instance ran by @stux who is a hobbyist irrc. They also run multiple other instances under cool names. Just like the instance I'm under, mastodon.coffee , is also ran by Stux