There is a reason for the two sets. In 2019 Crayola set about revamping many of their Special Effect crayons by expanding each product line with more colors and using the opportunity to rename both colors and even the product lines in some cases.
For 2019 they revamped four product lines: Glitter, Neon (which was Neons), Pearl (which was Pearl Brites) and Metallic (and technically they had been using Metallic FX for decades)
Then in 2020 they added another: Confetti (which was a revamp of Crayola Mix-Ups)
But really, to understand Crayola's special effect crayons, we have to establish what is and what is not a special effect line of crayons.
The simplest definition is that special effect crayons do something other than lay down their colors.
Before we take a look at how many Crayola has (or had), let's take a look at some of the crayon product lines that are NOT special effects.
First we don't want to confuse special effects with special purpose. Special purpose crayons have been around since their inception. Staonal was created before even Crayola and it is certainly a special purpose crayon. They are used for industrial applications. Here are some more examples:
Then we have other types of crayon product lines that also are not special effect crayons. These are crayons from Washable to Erasable to crayons that lay a thick rich amount to oil pastels. Here are some examples:
So with that established, what product lines are special effect crayons. Well, through their history we have many. They started with Fluorescent back in 1972 and many of their product lines were in the 1990s and early 2000s. Some were successful and had long runs and many were not and were only around for 2-4 years. Here's a visual:
Finally, lets take a look at the product run dates for all of these. When were they available? I've created a timeline to visually show them.
Going back to the assortment of crayons, even that has been done before. In the 1990s they did some boxes with groupings such as "Glitter and Neons" but they had one 48-color box in 1999 that was specifically called Special Effects. For collectors, it is a highly desirable box and not that easy to find.
If you are interest in more detail, I have some product line pages on my website that give full details on each product line (history, photos of all the box variations, colors, crayons, etc.). Not all product lines are there yet. I'm slowly adding to it so check back every so often (be sure to refresh the page...sometimes your cache will only show the older version of the page and you might miss new links).