Hi, I was able to find your support ticket #185654. Sorry if the answers you received seemed a bit confusing. If a similar situation occurs in the future, please ask further follow-up questions in your support ticket directly and we will do our best to assist you over there. If needed, we can even get in touch with the Phoenix dev team or other teams.
Phoenix is a simulation software. You can use it to create things like water, fire, smoke, and more.
You can then render those simulations with either V-Ray or Corona. You are not limited to using Phoenix specifically with V-Ray or Corona.
I would suggest starting here to learn the basics of Phoenix:
https://docs.chaos.com/display/PHX4MAX/QuickStart+Guides Once you are happy with your result (for example a fire or smoke simulation in Phoenix) you can decide whether to render it with V-Ray or Corona.