Further discussion has arisen from the synchroblog on interreligious dialogue.
I guess to me the differences between the different styles of communication are as follows:
Interfaith dialogue: Hello, I am a Pagan. I honour both the masculine and feminine Divine, and a multiplicity of deities immanent in the world. I would be interested to hear about your religion.
Evangelism: Hi, I'm a Pagan, and I'm here to tell you that the Goddess really loves you and is yearning to connect with you. She can make your life so much more meaningful.
Proselytising: Hi, I'm a Pagan, and I'm here to tell you that if you don't honour my specific vision of the Divine, the consequences will be disastrous (both cosmically and personally).
(Last 2 styles of communication unlikely to be heard from Pagans, though you might get Baha'i-style "all religions are one" type statements from a few Pagans, or "Jesus was a Pagan really". No. He wasn't. Really.)