Potential energy and work done are the same thing as much as kinetic energy and work done are the same thing. Potential energy is a state of the system, a way of storing energy as of virtue of its configuration or motion, while work done in most cases is a way of chaning this energy from one body to another.

For ex when a body is dropped from a height, its gravitational energy a virtue of its configuration with respect to the earth is converted into kinetic energy a virtue of its motion, due to the work done by gravity in bringing it down.

Is potential energy and "work done" the same thing?
If I connect to my e-mail server via SSL (SMTP/SSL) and the recipient also only checks his e-mail via SSL (web/https or IMAP/SSL), does this - generally speaking - increase the security for the message content in any way? 

That is, will the communication between my providers e-mail server and the recipients e-mail server be "secure"(*), or will the e-mail be delivered plain text between the servers? 

(*) Secure in the context of: encrypted throughout it's transit. Not secure in the sense that I'd put any really sensitive info in there.
