I wonder what the difference,if there is one, is.
I don’t think mine would count as special interests.Having said that about them not being ‘special interests’ I do become fixated on them to the neglect of other things.
Pre internet: Making cassette tapes by artist/genre/year etc. Writing lists of songs by genre/year etc.
Internet: Checking my rss feeds and twitter etc over a dozen times a day for articles to post on facebook/forums/twitter. Mostly mental health and politics.
Pre internet I would go to my local library and scour books on mental health and psychology.
A lesser /more sporadic interest over the years has been genealogy/traditional and dna.