As mentioned in an earlier post, we at Kent County Public Library explored our Open Source ILS options, setting up servers running both Koha and Open-ILS (Evergreen), the two main open source options. We read their web sites, tested out their interfaces, poked around in some code, joined their mailing lists, asked questions, and got quotes for migration and support. Liblime is the main support option for Koha, and Equinox is the primary option for Evergreen.
On the whole, we were impressed by both products. I felt that both systems easily rival the products of the big name companies in integrated library systems in terms of functionality and usability. Both systems have large communities of users and developers actively working to improve the software, according to the needs of their users. And support is available for migration and ongoing usage, not only through a contract with one or more supporting companies, but also through the community of users. And no, this isn't just theoretical, I've already received a lot of help and answers to my questions through the community mailing lists.
Since both these products are continually evolving, any comparisons must be taken with a grain of salt. And since they're both open source, it's entirely possible, and even likely, that they will cross-pollinate and each will take on features of the other, within the constraints of their basic frameworks. That said, here's my attempt to compare the two....
There are two main differences that tend to matter most to people considering an open source ILS. Koha already has functional Acquisitions and Serials Modules, while for Evergreen these modules are still under development. Evergreen has more administrative flexibility, which among other things means that sharing a single catalog among multiple library systems in a consortium is practical, if you wish to do so.
If your library needs acquisitions or serials modules and needs them now, then Koha is probably the way to go. If you can get by without these modules, or you can stand to wait a little while for them, then I would recommend giving Evergreen a very serious look.
As I understand it, Evergreen's greater administrative flexibility makes it possible to set circulation and holds rules at the consortial, system, and branch levels, meaning that these decisions can vary from location to location, rather than having to force a consensus among independent decision makers. Similarly, permissions can be set for groups of staff and individual staff members, and among groups of patrons, giving everyone the ability to do exactly what they need to be able to do, while minimizing the chances of unintentionally changing something related to another branch or library system that they don't need access to. So that's how Evergreen makes a shared database within a consortium practical. Look for a future post on why a shared database might be advantageous.
It's tempting to overgeneralize and say that Koha is for individual libraries while Evergreen is for consortia, but that's not true. Evergreen has features (described above) that make it ideal for consortia, but for an individual library that won't necessarily make use of all its features, there's no harm in having them, and they could come in handy someday.
Another consideration is the look and functionality of the OPAC (online public access catalog), which patrons use to find books and other materials. Demos of the Koha Zoom (newer interface for Koha) and Evergreen interfaces are available online. As you explore these interfaces, try to keep in mind that the look (colors, images, layout, even text) is very easily customizable compared to functionality which can be trickier to change.
Personally, I love the feature in the advanced search of Evergreen where you can group formats and editions, and would like to see that as the default option for all searches. On the other hand, Koha has a Federated Search feature, which is a good idea, but could stand improvement in its implementation. In its current state, rather than offering federated searching on your search terms when there are few or no results, you only get the option to do a federated search for the title of an item you've already found in the catalog.... Hopefully this feature will be re-worked in Koha, and perhaps Evergreen will add a Federated Search option as well.
I have tried to fairly represent the comparison between the two software systems, but I'm sure my personal preference has shown through to some degree. If it sounds like I like Evergreen better of the two, it's because I do. Evergreen is the system that the Kent County Public Library has decided to use, and I'm very much looking forward to the switch.