You mean in terms of fabrics being interchangeable? Many fabrics can be used for both suiting and jacketing as far as material goes. Some things - such as Shetlands or loose open weave tweeds - are not ideal for suiting as the trousers can start to sag and look after a while. I am going by hearsay, but that seems to make sense. Of course, many fabrics just "look" like they should be either for a jacket or a suit.