OpenBSD has two types of "partitions":
- disk, or "real" partitions
- disklabel partitions
partitions function like you would expect on linux. they are GPT or MBR sections of the disk. OpenBSD does not impose any limitations outside of what GPT and MBR disks have. you manage these types of partitions with fdisk, which is notably different from linux's fdisk:
$ man fdisk