@aswath Just as Mastodon is a federated alternative to Twitter, @pixelfed is a federated alternative to Instagram.
Mastodon is a microblogging platform. @pixelfed is a photo gallery platform.
Unlike Mastodon, @pixelfed lets you edit and apply filters to photos. You can also add custom licenses to your work and create your own portfolio too.
Anyway, I highly recommend that you create accounts on other Fediverse alternatives so you can figure out what differentiates each of them.