The first graph below shows the development of content categories on reddit over time, in the beginning, much like steemit, reddit only had one front page so it may be useful to compare how reddit evolved into what we know now.
2005 - In the beginning, Reddit's creators help seed Reddit with numerous fake accounts
2006 - Apart from "reddit.com", "NSFW" is the most popular subreddit at the beginning of 2006. "Programming" becomes the second most popular subreddit for most of the year. Then by the end of the year, "science" gets launched and soon becomes the third most popular subreddit.
2007 - For most of the year, "science" and "programming" are the most popular subreddits (apart from "reddit.com"). They then get displaced by "politics" as the most popular non-"reddit.com" subreddit towards the end of the year.
2008 - This year is dominated by the launch of numerous new subreddits. By the end of the year (except for a short-lived blimp following the 2008 Presidential election), no one subreddit (not even "reddit.com") would capture more than 50% of Reddit's attention. From the beginning of 2008 (to at least the end of 2012), there is a continual exponential increase in the number of unique subreddits people submitted to each week.
mid-2010 - Reddit overtakes Digg in search popularity.
2010–2012 - From the beginning to the end of 2010 (and following Reddit's move to Amazon AWS servers in November 2009), Reddit more than triples in page-views and bandwidth count. By February 2011, reddit reached 1 billion page-views per month. Within a year (by January 2012), Reddit again doubled in pageviews and reached 2 billion pageviews per month.
2010–2012 - Top-level content on Reddit transitions from majority text-based to majority image-based. On January 1, 2010 - 27/100 of the top posts were images. By January 1, 2012, 77/100 of the top posts were images.
2012–2014 - Reddit achieves 37 billion page-views in 2012, 56 billion page-views in 2013, and 71.25 billion page-views in
2014 - Yishan Wong serves as Reddit's CEO from March 2012 to November 2014. By September 2014, Reddit raises $50 million in funding in a Series B round, and makes its first app acquisition in October 2014.
Steemit
Graph showing the current data for popular categories for steemit, it shows that steemit related subjects are most popular followed by personal blogs and the introduceyourself category.
In comparison to reddit steemit has a more varied range of subjects than reddit did when it started. Reddit started with a large emphasis on programming, I think this can be compared to steemit related subjects on steemit, many of which are related to programming.
No doubt the economic aspect of steemit will influence which categories become popular, I believe it will create a faster and more efficient value discovery of what users find important
Steemit Popular Categories
Top Paying Categories (July 2016)
The next 10
Conclusion
We are only able to compare the first part of the reddit graph with steemit which shows a strong correlation in terms of amounts of popular categories, however the subjects of the categories are different. One of the main differences is that NSFW content was extremely popular at the start of reddit's evolution whereas it not a main category in the steemit results, I believe this is because the value proposition of steemit as opposed to reddit which placed no real-world value on content discovery, only imaginary.
Steemit differs due to the introduction of real price discovery for content, receiving a down-vote on steemit carries real-world economic consequences for the user, therefore it is not in a users interest to abuse or try to game the system but to participate constructively. Steemit is also decentralised which may account for the popularity of steemit and personal subjects as people place great value in the platform itself and therefore themselves.
Thanks to @calamus056 @steemrollin for steemit graphs