Ideas need to be translated into visuals which help turn an idea into a product. Visualising a concept means you’ll need some or all of these: sketches, illustrations, technical drawings, mood boards, line sheets …etc
Samples are prototypes made to model design ideas and made in order to finalize the pattern for production. Sampling should take place during the first phase of design (R&D) because you can’t get to selling (second phase) if you don’t have production (third phase). There are a few types of samples usually made, the main ones being prototype/toile, 1st sample, sealed/final sample, salesman sample, pre-production sample.