Developers, managers, and builders. Terminology question.

Traditionally Drupal was used by hobbyists, some of whom are programers, some not. Increasingly it is used by enterprise users who need a team of specialists. In between are small to medium business and nonprofit sites, often built (often badly) by web shops and then run (often badly) by someone in-house who knows a bit about the site, possibly with the help of a freelancer who charges by the hour for adding features, maintenance etc. more or less well or badly (I do this type of work).

In Drupal you can achieve a lot by installing and configuring modules and it can get quite complex. A site builder does that, and may never touch a line of code but it is still a skill in itself because Drupal is so complex. For many tasks you can alternatively write code yourself (and if there is no module for the feature you want, you might be obliged to write code yourself). A developer does this, but of course there is an overlap with site builders. A big site might use several developers, like any large software project, and they should all know Drupal as well as general programming skills, if the end product is going be of good quality. Also theming can be done partly by tweaking settings in the browser and partly by writing CSS and JS code and some simple PHP. A frontend developer specialises in this, and will often make the theme more by coding than by tweaking settings in the UI, and a site owner who can put a lot of money into achieving a highly professional result will have the theme written by such a specialist. A big site will also have the funds to hire a professional graphic designer, and a user experience specialist to design the site. A project manager manages this team and communicates with the customer to make sure it is all working well, on time, on budget, etc. So Drupal can be anything from a blog which you get working in an hour, to a large site which takes a highly skilled team 18 months to pull together.

Often I say to clients, 'when you tell me what you want to do, in Drupal we can get a lot of that working fairly cheaply by installing a few modules; on the other hand if you want a highly streamlined slick site which does much the same thing but which just feels and looks very 'professional', and is very reliable, the time, skills and cost required will be much greater. This is also true if the site has a huge amount of content or a huge number of visitors. So having a site built by a team of real Drupal specialists is the right choice for a large organization who can afford the exponentially higher costs.

To give my own take on John's nice response: I don't believe there is any standardized definition for these, but as a general idea they are:

Drupal site builder - this person has a wide knowledge of Drupal modules and themes, and will be able to bring these all together and configure them to do whatever it is a given site needs. This person may also know how to create
Drupal developer - this person has a wide knowledge of Drupal's APIs (programming interfaces) and will be able to create custom functionality on a website, and integrate with existing modules and themes
Drupal project manager - this person is the leader on the team and will facilitate communication between the client and the team