Community distributions, by definition as well as the preferences of their members, are far more informal than commercial ones. If you are a programmer, you may welcome this informality as a comfortable and familiar environment; however, if it is new to you, it can quickly drive you to distraction.
For one thing, association with a community distribution is voluntary. In the absence of a paycheck for most members, all that keeps them involved is their own interest. Inevitably, this situation means that community distributions are more democratically organized. Leaders of community distros not only can't give orders the way that managers in a business can, but their authority lies largely in their diplomacy and arbitration skills.
In this situation, you cannot expect quick decisions. Instead, in a community distro like Debian, every point is discussed until everyone is exhausted, and the issue may be voted on by all members. Technically, a distribution like Fedora operates as a representative democracy, with community members electing a board, but these representatives usually know better than to make decisions without gauging the opinions of everyone else. In both these cases, obtaining at least a rough consensus is at least as important as taking decisive action.
The informal structure is also reflected in the forum-based support that community distributions offer. Such help is largely an offshoot of a member's involvement in the community, as well as another way to contribute and gain credit. In many cases, this help can be quicker and more detailed than the formal help that commercial distributions sell, but also harder to find, sometimes much ruder, and frequently continuing long after you have solved your problem as new people chime in with suggestions. To someone used to the commercial way of doing things, this support can be disconcerting, even though it is often just as effective as that offered by paid technicians.
Another unbusiness-like attitude of community distributions is their indifference to regular release schedules. This indifference is due partly to a preference for quality rather than punctuality, since credit for good work is the only return that many members will ever get for their volunteer effort.
However, it is also due to the fact that, given online repositories, regular releases are largely irrelevant, because the newest versions of applications are always available anyway. At most, a formally scheduled release is an excuse for extra testing and rethinking distribution policy. That is why Debian's deserved reputation for being slow with new releases does little to affect its popularity. But, in fact, many community distributions have lapses just as bad as Debian's; for example, the lapse between CentOS 4.6 and 4.7 was over three years.
True, community distributions associated with corporate interests have become more regular in their releases than they once were. Significantly, though, when faced with a loss of development time because of the Red Hat security crisis, Fedora responded by delaying its next release, preferring to do it properly, just like any other community distribution.
In comparison, like any software business, a commercial distribution needs new products -- which is what a new release largely is. Moreover, keeping to a schedule is a sign of reliability for customers (especially corporate ones), many of whom are still thinking in proprietary terms, and are unused to the constant upgrades that are the norm in GNU/Linux.
These are probably the reasons why Mark Shuttleworth sees a need to promise regular releases in his blog, and to float the idea of major distributions coordinating their releases with major applications like GNOME. What is largely irrelevant to community distributions is essential to corporate ones.
Probably the largest difference between community and commercial distributions is the philosophies that motivate them. Sometimes, this difference is attributed to the difference between the activist free software and the developer-oriented open source philosophies. And it is true that distributions that contain only free-license software like GNewSense are usually community-based. However, you can find many gradients between the two poles of free software and open source in both types of distros, so this description seems lacking.
Instead, I would characterize members of a community distribution as seeing their involvement as a way of life. Whether they are free software advocates who wish to contribute to user freedom or open source advocates for whom their work methods are a way to improve software quality, members of a community distribution tend to see themselves as working for something larger than themselves.