I found the article “New Metadata Standards for Digital Resources: MODS and METS” by Rebecca Guenther and Sally McCallum to be really helpful. I felt like I’ve heard both terms bandied about with only a general understanding of what they are and how they work. The clear definitions and examples really helped me grasp both the complexities and the excitement that MODS and METS can provide to the library world.
MODS allow a solid level of description and definition for records and has a good crosswalks to and from MARC 21. While having such a rich format like MARC 21 has provided libraries with interoperability it can also make transitions very difficult as there is such a backlog of materials to convert. Since MODS are already providing a middle ground for definition between MARC 21 and simpler schemas such as Dublin Core I wonder if they might also provide a good crosswalk to future systems such as a FRBR system. In any case, it is exciting to see the world of digital resources supported by a strong metadata standards.