These are the most salient differences in my experience with both:

- Apart from saving the parsed, "readable" version of an article, it can also save the web as-it-is. This is very useful for those times when the formatting is important (as it is in articles that include code; you loose syntax-highlighting with the readable view. Pocket can be set to try and choose the best view for each article.

- It does a great job with videos.

- It uses tags instead of folders.

- Instapaper has been less reliable for me (specially the android app), although in fairness I've used it more, so I'd notice it's unreliability more often.

I'm not that interested in recommendations, but I gotta admit that the few times I've looked at them, Pocket's recommendations were fairly good.

I've been using Instapaper for around two years now, keeping Pocket as a bag of less-important links, not-really-reading-material, and very often video. I was thinking of going back to Pocket as my main read-it-later service, specially for the first feature I mentioned.

It being Mozilla-owned and some day also OSS will surely be a further advantage in my mind.

Nowadays, I add an article to both Instapaper and Pocket. I used to use Pocket a lot but sticking on Instapaper more.

Things I love about Pocket are

- Curated (and from other people I followed) "recommendations",

- tags "Best Of", "Quick Reads".

- beautiful android app

Instapaper has less features than Pocket but I find that

- Instapaper article parser is better,

- UI is cleaner, highlights ( I love these!),

- ability to switch style (type faces, article background)

- speed read

- they also have "Browse" (something similar to Pocket's recommendation?) but in Android app, it's a bit hidden in the drawer menu so I don't use it often.

Pocket has clients on more exotic platforms, such as the Kobo eReaders.