As mentioned in this article, Computer Aided Design (CAD) consists of three modeling paradigms. Parametric and direct modeling are the two most common ones.
In both modeling standards, you create sketches (2D drawings) and generate bodies from those sketches with specific tools. Aside from this, they are fairly different:
Parametric modeling  Direct modeling  

How do you create computer models from sketches? 


How do you adjust your 3D model? 


How easy is it to adjust your 3D model? 
It’s not so easy. If you have a complex model that was created from hundreds of modeling features, you need a deep understanding of how the model was built and how its geometric relationships were created, so you don’t break the model when you make changes. 
It’s easy. If you import a CAD model into Shapr3D, you don’t need to know its complex feature relationships. In fact, the model should not contain parametric data—only the raw geometry remains—because those are removed in the export process. 
As you can see, direct modeling is an effective, quick, and straightforward way to explore ideas and design variations, especially in the creative phase of a design project. On the other hand, parametric modeling is a systematic, mathematical approach to 3D design. The complexity of parametric modeling requires extensive training and learning, and it can take years to master parametric modeling software. In comparison, it’s easier to pick up and learn direct modeling, or Shapr3D, specifically.