I just copy&pasted their README in chatgpt asking for a comparison (so there may be allucinations)

Both PrivateBin and Paaster are "pastebin" tools that allow users to share snippets of text or code online. Both emphasize privacy and security, encrypting data at the local level in the user's browser before sending it to the server. However, there are several key differences between the two services:

1. Design and User Interface: While PrivateBin self-identifies as a minimalist pastebin, Paaster seems to put an emphasis on user experience, offering features like file drag & drop and a paste history.

2. Features: Both offer basic features like password protection and the option to delete data after reading, but PrivateBin also offers features like the ability to have anonymous or nicknamed discussions, Markdown formatting support, code syntax highlighting, and the ability to upload files. On the other hand, Paaster offers a paste history feature, PWA support, and i18n.

3. Trust: PrivateBin warns users not to blindly trust the server administrator, whereas Paaster advises users to either host their service or use a trusted hosting service.

4. Implementation and Maintenance: Paaster seems more developer-oriented, with API documentation, a CLI tool, and support for Vercel and Docker. PrivateBin, however, also has a developer and installation guide.

5. Hosting Options: Paaster seems more geared towards self-hosting, with detailed instructions for use with Docker and options for use with external storage services like Amazon S3 and Google Cloud Storage. PrivateBin does not provide specific hosting details in the provided text.

6. Security: Both use end-to-end encryption, but they use different encryption algorithms. Paaster uses XChaCha20-Poly1305, while PrivateBin uses 256-bit AES in Galois Counter mode.

These are just some of the key differences between the two services. Both have their strengths and unique points, and the choice between the two will depend on the specific needs of the user or organization.

Actually I did a Pros/Cons for Paaster compared to PrivateBin awhile ago here

https://github.com/privacyguides/privacyguides.org/issues/2015

Basically the TL;DR Modern encryption, doesn't expose metadata, modern design (svelte + asyncio python), pwa support, frontend / backend code separation & paste history.