He has highlighted the differences between the two in the description:
Unlike Clickbait Remover, DeArrow's main purpose is for crowdsourcing better titles and thumbnails
When a crowdsourced title is not available, DeArrow will auto-format it according to your setting, but does it in a more sophisticated way than Clickbait Remover. Instead of only setting all words to lower case, or capitalizing every word, DeArrow supports casing systems such as "Title Case" and "Sentence case". These will still allow acronyms and proper names to remain capitalized.
When a crowdsourced thumbnail is not available, DeArrow by default shows a screenshot at a random timestamp in the video. Clickbait Remover's thumbnails use YouTube auto-generated thumbnails, and while they are seemingly random, they are chosen by a machine learning algorithm to favor faces with expressions, and other overstimulating features. DeArrow uses truly random timestamps generated by its own server. DeArrow will also check the SponsorBlock database to ensure the randomized thumbnail is not inside of a sponsor segment.
SponsorBlock profile:
Profile Picture > Settings > Sponsor Block > (scroll all the way down) > Import/Export > (select and copy all the text) > (save this copied text in a text file OR pin it in your keyboard's clipboard) > (Now Go to new app and paste in Import)
I switched from ReVanced Extended (RVX) to ReX using my exported settings. Doing it this way makes switching APKs a breeze.