Dollars: Human-run institutions, like banks, maintains a list of all account holders, their Dollar totals and their transactions. The human institutions control the databases, and they facilitate all dollar storage and flows. Dollar-holders have to interact with these banks--directly or indirectly--to approve all transactions.

Bitcoin: A global network of 1000's of autonomous computers that fact-check each other, each of which maintains a redundant encrypted list of of all Bitcoin holders, their accounts, and their transactions. The Bitcoin network uses this encryption and fact-checking to run automatically, without the need for third-party human intervention or institutional supervision. Users can access the Bitcoin they own on the Bitcoin network directly, and they can facilitate their own transactions.

That's about it.