Tom, I understand your confusion, it's ok, we've all been there. It is important to understand what is the best fit for each feature. Let me give you a hint.
Basically, there are a few ways of storing custom table data in Kentico (as SQL tables):
- Custom Tables
- Module Custom Classes
- Page Types (and pages in the CMS tree)
- Forms (bizforms)
First three options should be used for content or something like that. When this data is populated by CMS admin or synchronized (imported) from third-party systems. It could be custom dictionaries, pages, products, locations, etc. To learn more when you should be using each option I'd recommend reading Sean G. Wright's blog post where he is explaining this in detail.
The last one, Forms (also called bizforms), is purely designed to store data captured on the frontend of the website. Something like contact us, register for event, sign up for newsletter, product enquiry form.
So, all in all, if you describe in more detail what you actually need to store or what the function is, it will be easier to help you because as you can see there is no golden standard of storing the data and all depends on your case. I hope it makes more sense now.