The Blocks table contains bare block information (timestamp, witness …)
Each block can contains Transactions
Depending on each transaction type, the associated transaction’s data is stored in the related table.
Virtual operations are operations resulting from the activity of the blockchain but, unlike transactions, they are not initiated by users.
More information about virtual operations tables (VO…) can be found here
The Accounts table is a non-transactional table and contains a list of all accounts and related information resulting from activity of accounts on the blockchain
The Comments table is a non-transactional table and contains all posts and comments and the related information resulting from activity related to posts on the blockchain (updates, votes, …)
The Followers table is a non-transactional table which enables to know who is following who.
The Reblogs table is a non-transactional table which enables to know who “resteemed” which post or comment.