positional or functional isomers?????????????

Can't be positional isomers...carbon skeleton is different. One is just Ph and the other is Ph-CH₂. They're not functional isomers either, as a necessary condition is that their molecular formulae must be the same, which is not the case.

in RSM ITS GIVEN FUNCTIUONAL ISOMERS

It's more like a part of a homologous series!

I think its a chain isomer,length of carbon chain different......I also have RSM and I have found quite a number of ans wrong.