How can I make sure I am connecting via OpenVPN protocol?

[captainp0w3r]

My VPN provider has it's own client they suggest I use but beyond server location, I cannot alter anything. They have told me via email that their client uses OpenVPN but how can I make sure it is and not using PPTP or L2TP? I'm just trying to way out the simpleness of their client vs just going with OpenVPN's client and their settings.