[angry_octet]

The Tor client is the software which runs the 'onion routing' part. This provides a local network port which is your wormhole into the network; this is called a SOCKS proxy.

The TBB has the Tor client and a browser (a slightly tweaked Firefox) configured to connect via the Tor SOCKS proxy rather than via the standard network.

I was disappointed last time I booted up TBB to see they had security by default set to 'Low', which enabled lots of unnecessary stuff, like javascript on for every site by default. Too many content parsers trying to do stuff with untrusted data. Its pretty poor.