What is Plastic Design in Catia V5?
How is it different from choosing the ''plastic" from material after designing a component using Part or GSD etc..
I guess you're asking about the new Styled Plastic & Packaging product that Dassault announced in March, 2017?
Based on the press release, it seems to be a combination of several CATIA products, along with some new capabilities tailored to the plastic packaging user. It doesn't seem to be based on the Part Design and GSD that everyone in used to, but instead it's based on Image & Shape Design and Functional Molded Part Design with Smarteam managing all the data.
So, Yes you can do plastic design with the old tools, but this new product probably provides newer, better and faster tools streamlined for plastics.
(you can also use Part Design and GSD for designing thin, bent parts, but you would probably prefer to use the Sheetmetal Design workbench instead)