The first difference is where it lives. An app lives on your phone and wants installing, updating and signing in to. Plamfy lives in your browser: you open it, arrive as a guest and tap the Live tab. If you want an icon, you add it to your home screen, and that is the whole set-up.
The second is how watching works. On Plamfy, the rooms that are open right now sit in the Live tab of the video feed and on the Live side of the Who's online page. You swipe up or down to move between rooms, type in the room chat, send gifts and follow the people you like.
The third is the private call. Every Plamfy room has a Start Video Chat button at the bottom, and room cards and profiles carry a video button too, so going from watching her to talking with her is one tap, explained step by step on the private video chat page.
The fourth is who can stream. On Plamfy, viewers can't. If you came from an app where you sometimes went live yourself, that part won't carry over: here, you are always in the audience.
The fifth is language. Text messages on Plamfy can be translated automatically, so a different language isn't a wall. For a site where many of the people streaming live outside the US, that small feature does a lot of work.