@kari I'm struggling with the same thing, and posted (microblogged?) about it here.
AFAIK
- kbin link, photo, and video submissions are analogous to link submissions on reddit, and to new posts on lemmy.
- kbin article submissions are analogous to text submissions on reddit (and also new posts on lemmy since it doesn't seem to make a distinction between link and text submissions)
- kbin post submissions are an anomaly, untitled posts like twitter tweets or mastodon toots that technically go into a magazine (/m/random, unless another is chosen) although they are displayed under the microblogs header rather than threads.