Both have similar functionalities. But, instapaper allows only 5 free highlights/notes per month. Pocket allows 7 free highlights per article. You can just use either of these platforms to add whatever content you want to consume.
2. Instapaper has a folder based organizing system. Pocket has tags based organizing system. Pocket edges out in this as tag based searches are powerful.
5. Instapaper has a speed reading feature while Pocket has a text to speech functionality which is quite good.
6. This is where instapaper edges out - IFTTT has more actions based on instapaper, only one based on Pocket.
1. No archiving feature. You can't archive all notes into a pre-defined archive folder and keep your All Notes folder clean with current items.
2. No ability to check out just the annotations and highlights in a particular note.
3. No double backlinking feature. Takes manual effort. You can use tags - but not exactly like it.
5. Only 2 devices can be used in free version. Good enough for most people.