Dual Homed Host and Proxy services

[kwakh @ ctrvax . Vanderbilt . Edu (Joon)]

I have some question for the experts on firewalls.

Well, I'm in process of learning firewalls. 

This makes me very confused..

What's the major difference between dual homed host architecture and proxy
services?

This is what I understand so far.

Dual homed architecutre: Users have to log in.

Proxy services: Users don't have to log in. Recommended over dual homed.

Also I don't understand this sentance "The proxy server runs on the dual
homed host."

If this is true, then dual homed host run proxy server program and also
bastion host can run proxy service program?

But proxy service performed by bastion host has a superior quality.

Is it ture????

I'm all confused now..

Please enlighen me...

Joon...