Just create several different content types, Orchard is all about being able to reuse the parts and fields you make for different content types. No reason why you cant have a bunch of similar but slightly different content types.
For your article content type, as they are the same, have you considered using Taxonomies to classify your articles? So create a taxonomy of ArticleType with all your different article types: How To Article, Overview Article, etc. Create a Article content type and attach a taxonomy field linking to ArticleType so when you create an article there will be a list of available articletypes to classify said article as. Can easily add more later if the need should arise.