I’ll mostly be referring to WordPress themes and the three common styles you’ll find in the repo. However, the same basic ideas apply to all website templates and web design in general. This is what each means to me and does not necessarily represent what everyone else in my industry thinks. It’s a bit subjective, but based on my experience and knowledge I think my ideas are well-founded.
It is a cliche to use building a house as an analogy for web design, but for good reason. It just makes sense.
The foundation, cement and rebar to support a frame.
(PHP, functions, files, theme folder, etc.)
Boilerplates are generally useful to web designers and developers who don’t want to reinvent the wheel, but just need the basics to get started. Once they get going, they’re fully capable of building out something completely custom.
The frame, a skeleton or structure to symmetrically shape out the width and height of areas of the house to support the look.
(HTML, divs, width, height, padding, margins, structural CSS, etc.)
Frameworks are generally useful for designers and new websites that need everything ready to go and they can just add their own content, graphics, colors, and fonts.
The look, the drywall, paint, and carpeting.
(visual CSS and graphics, colors, fonts, etc.)
Themes are generally useful to the basic end-user that has little to no code experience or interest and just finds something they like and then set and forget.
Yes, they’re all technically “themes”, but these are the common theme style variations for very different purposes at your disposal. If you’re interested in building something from scratch eventually, boilerplates, frameworks, and themes are very good learning tools to get started with until you have the necessary skills.