This is something that I hear quite often, when talking to vendors or prospective purchasers:

Myth: Content management systems are pretty similar in capabilities, and are rapidly converging on a single feature-set.

In my experience, however, this is far from the case. Instead, I would say:

Reality: CMS products have less than 30% common capabilities, with huge variation in designs and approaches. Moreover, vendors are still looking to distinguish themselves in a crowded market, and products are therefore continuing to diverge.

From what I’ve seen, vendors have all taken a different approach to the development of their CMS products, based on: technical architecture, strategic vision, key markets, key areas of capabilities, and more.

The net result is that while they all have roughly similar areas of functionality (authoring, workflow, versioning, publishing, etc), it’s how they provide capabilities in these areas that are different.

Some random examples:

• Some products are specifically designed to support sites that are only three levels deep (which can be an advantage as it offers simplicity), while others have been engineered for huge sites (which can be good or bad, depending on your needs).
• Every product offers some metadata capabilities, but I’ve seen dozens of different interface designs, methods of configuration and administration.
• Workflow can range from a single checkbox saying “Page is live” through to graphical interfaces for dragging-and-dropping workflow steps.

You get the idea… in practice, it’s these differences which will make or break your project.

I also don’t see products converging on a common design or feature-set in the next year or two either. At present, the competitive pressure is still driving innovation, and there is no advantage in consistency.

It’s for this reason that I recommend a requirements-driven selection process.