What is the difference between Catalog and Custom?
The two start modes differ in where the image is stored. Catalog images are hosted by the system — open an invite link and you see the picture. Custom images stay only in the local browser and are never uploaded; each participant needs the same original file to show the picture.
Catalog start: open the link and see the picture
Catalog images are hosted by the system. In rooms started with them, friends only need the invite link to see the same picture — no separate file transfer.
Custom start: the photo stays local
Photos chosen under Custom are not uploaded to the server; they stay only in the browser used to pick them. Clear site data and the image cannot be restored. Deleting your account does not affect copies on other devices, because the server never stored the image.
For friends to see the picture, they must choose the same original file in their browser, with identical pixel width and height.
Choose by need
Want anyone with the link to see the picture? Use Catalog.
Want a group photo limited to specific friends? Use Custom, and send the original file with the invite link.
Both modes puzzle normally — but do not mix them in one room: catalog rooms work from the link alone; custom rooms need the original image sent separately.