I can only partially answer this as I've never played Swordplay, I always played Warrior Heroes before Talomir Tales, so I can't comment on how Talomir Tales plays compared to Swordplay.
I can comment on the encounters. When you buy a Talomir Tales rule book, you get 14 different encounters which you can customize to fit any game you wish to play, you also get an additional 16 encounters that link together to form a mini-campaign very similar to a D&D adventure or Pathfinder module. The 16 additional encounters are variations to some of the 16 base encounters which are "tuned" as you say to fit the story line. I'll give an example shortly.
The scenario books are only the 16 (or more) encounters used for the adventure & do not contain all of the rules found in the rule book.
Now for a few examples. There are 14 base encounters in the rules, but Piathoe's Peaks actually uses 11 of the base encounters & that means some of the encounters are used more than once. A scenario may require more than one raid for instance or the exploration of more than one monster's lair.
Some of the other things you may find in a Scenario book is additional creatures and races. Piathoe's Peaks, again as example, introduces stats for Amazons, Bugbear, Gnolls, a Mountain Nymph & a trio of demons.
In addition to the settings for the encounters, the scenario books have pre-generated Characters & NPCs you can choose to use in your game. And last but not least there's usually a magic item or two that you could use in your games.
Why 16? Well, it's so a more complete adventure setting can be created & played.