dblp classifies publications by the following types:
Books and Theses
In this category, we list authored monographs, as well as PhD theses. Edited monographs, such as proceedings or collections, are listed under Editorship.
Articles that have appeared in a peer-reviewed journal fall into this category. Due to technical limitations of dblp, editorial articles and prefaces are currently also listed under this type if they appeared in a peer-reviewed journal.
Conference and Workshop Papers
This category lists papers published in peer-reviewed conferences or peer-reviewed workshops. Since it is hard (or even impossible) to draw the line between conferences or workshops in computer science, we do not make a distinction between those two types.
Parts in Books or Collections
Research articles that have been published as a chapter of a monograph are listed in this category.
All publications that have been edited by a person go into this category. This type is intended to also include prefaces and editorial articles; although we are currently unable to make this distinction due to technical limitations of dblp.
Scientists occasionally author publications that are not meant to be original research, but rather reference material for computer scientists. Survey papers and encyclopedia entries fall into this category. Please note that in dblp this classification is still far from being complete.
Data and Artifacts
Evaluated and published research data and artifacts (such as software, multimedia supplements, VMs of experimental setups, etc.) are listed in this category.
Informal and Other Publications
dblp focuses on research papers that have been vetted in a strict peer-review process. However, papers published in online repositories without a strict vetting process, as well as as contributions to informal workshops, may still be valuable contributions to the scientific community.
Usually, 'informal publications' are publications that are not excluded from being republished in peer-reviewed journals or proceedings. Also, reputable online repositories like CoRR, ECCC, or IACR generally fall into this category; although if the listed publication is part of a peer-reviewed journal or a peer-reviewed conference proceedings volume, then we change the type accordingly.
As a rule of thumb, all publications that do not fall into into one of the other categories above are listed as informal publications.