panopoly comparison

Disclaimer: While I spent a lot of time with Panopoly back when Spark was first kicked-off, I've been pretty heads-down since then, so my knowledge here might be slightly out of date.

In terms of target audience, both are very similar. They are both aim to provide a better experience for content authors out of the box. Spark is focused primarily on doing so in core in Drupal 8, and using the Drupal 7 distribution as a means to this (see #1785438: Goal of D7 work on Spark? for more info), whereas Panopoly is focused on primarily doing so in Drupal 7, and will likely port their distribution to Drupal 8 sometime closer to release.

As a result of these two different fundamental goals, the architecture of the two distributions is slightly different; Panopoly uses the "Apps" model w/ Features, and Spark sticks to just vanilla modules because these things are not part of Drupal core. However, Spark uses many of the modules bundled with and pioneered by Panopoly (for example, Panels, Panels In-Place Editor, etc.) in order to provide parts of its authoring experience, and all of Spark's modules have been built as separate, standalone projects so that they can be incorporated into other distributions as well. (For example, the 7.x version of Drupal Commons is now incorporating Aloha module for its WYSIWYG editor.)

When we set out to build Spark, what we wanted to do was find areas in the Drupal content authoring experience that Drupal's competitors already have, but which were currently not being filled by any other module or distribution (in other words, provide a means for those people evaluating Drupal to have a "checkbox" to check next to competitor B). Brand new features like inline editing, responsive grids/layouts, mobile previews, etc. rather than things Drupal already does well. We actually had a call with Matt Cheney before kicking off Spark's development to get a sense of Panopoly's roadmap and ensure we were filling holes, not stepping on toes.

While the target audiences are very similar, there shouldn't be much overlap in what Panopoly provides with what Spark provides; they are both complementary. And while I believe that the Panopoly folks are planning to pull in Layout module's functionality at some point, they are probably holding off until the team gets focused back on Drupal 7 again (which will happen in drips and drabs until after April/"code freeze", most likely), since it is a bit buggy atm. :)

In terms of merging them, I don't think so. Both teams have very different end goals in mind: Spark's being UX improvements targeted at core stable version +1 and Panopoly's being targeted at "best of breed" contributed modules that are available today. But it's certainly my hope that both projects can and will continue to borrow/steal code freely from each other and help improve each others' code. That only helps everyone. :)

Hope that helps!

FYI: Looks like Spark is getting parity with D7 and D8 - http://spark.drupalgardens.com/blog
Would be great if we could keep some alignment rather than diffusion.