Compare 2 folder contents excluding extension

[GSXRMovistar]

Hi all, can anyone point me in the direction of an app that will compare the contents of two folders and flag the extra files in one of the folders? However I want to exclude the file extension, i.e. the first folder is a load of png files and the second is zip.

I want to identify the extra png files where there isn't a matching zip and get rid of them.

Thanks