The screens that you've posted are never to be relied on for the true price of a set of flights. These are not prices, only estimates, and the estimating engine can go wrong. If something odd appears to happen with the "pricing", it's almost certain that something is wrong on those screens; it often is.

You must click through to get a firm price for all the flights. Only then is it possible to say whether the app and the website are showing different prices. I would be extremely surprised if they do.

If they do give different prices when you get to firm pricing, then it would be interesting to see those screens, together with the fare + TFC breakdown for each.