No major difference its just what works for you. I used Hoarder (KaraKeep) in the early days but found I preferred the Linkwarden UI particularly on mobile so switched. But they’re both great.

Strangely I’ve found I tend not to use it for everyday bookmarks use (I’ve put those in a Joplin note). Instead I use Linkwarden for interesting stuff I might need at some point - long read articles or information for projects that I’ll be undertaking in the future, be that videos or written guides. You can set folders (topics) & tags for ease of retrieval.

I tried Hoarder (KaraKeep) & Linkwarden. Both excellent but I preferred the UI for Linkwarden, particularly on mobile, so I stuck with that - i found Hoarder awkward to edit thumbnails for example though things may have changed in KaraKeep. From Android perspective both have apps but I prefer to use browser plugin. With Linkwarden there’s some hoops to jump through on Android Firefox but it works perfectly once set up. Both excellent choices.