Warning: This is a very long post. If you are not interested in details about Hallmark Magic Ornaments, you might want to skip this post.
The vast majority of Hallmark Ornaments that we buy are magic ornaments. The USS Enterprise magic ornament in 1991 is what got us started buying Hallmark ornaments.
History of Hallmark Magic OrnamentsThe initial Hallmark magic ornaments were designed to plug into a light string. Remove the bulb from a miniature light string, plug in the magic ornament, and after Christmas hope that you remember where you put that bulb.

Hallmark then began offering magic ornaments with batteries (typically LR44 or for smaller ornaments LR41). And, Hallmark was nice enough to include these batteries with the ornaments. Some of the more recent larger battery-powered ornaments require 3 AAA batteries (which Hallmark does not provide). Hallmark continues to offer battery powered ornaments.
I believe it was 2009 when Hallmark introduced the Legacy Cord. With fewer Christmas light strings being offered with incandescent bulbs, the Legacy Cord accepted the plug-in ornaments made up through 2009. The Legacy Cord could only accommodate 4 ornaments. And, there were some plug-in ornaments that were not compatible with the Legacy Cord. The Legacy Cord was discontinued by Hallmark at the end of 2020.
In 2010 Hallmark offered Wonder and Light ornaments that connected to a Magic Cord. This cord allowed you to plug up to 7 ornaments in to the cord. Magic Cords can be connected to allow more ornaments on a "single" cord. 3 Magic cords can be plugged together. The Wonder and Light name has faded from use and they are just called Magic Cord ornaments. These ornaments offer lights, sound and motion. Magic Cord ornaments offer a basic level of synchronization between ornaments. The last Magic Cord ornaments were offered in 2020.
The Keepsake Power Cord was introduced in 2017. It has connections for 7 ornaments. Unlike the Magic Cord, you cannot connect Keepsake Power Cords to each other. The Keepsake Power Cord allows for complete synchronization and communication between ornaments. Many Keepsake Power Cord ornaments communicate with one another wirelessly. They do not need to be connected to the same Keepsake Power Cord to synchronize or communicate. The various Storyteller ornaments demonstrate this capability.
My Thoughts and Comments about Hallmark Magic OrnamentsThe plug-in ornaments were a bit of a pain as it was sometimes very difficult to remove the miniature bulbs. You had to make sure the bulb voltage was within a range that would power but not damage the ornament. The cords on the ornaments were thick and stiff and sometimes too short. But, they gave us the opportunity to have our ornaments light up and have sound and motion. Hallmark recommended no more than 3 ornaments on a single light string. Some of the later plug-in ornaments came with an adapter because some light strings had sockets that wouldn't accept the plugs on the plug-in ornaments.
Battery-powered ornaments are frustrating to me. Each year I get out the ornament, remove the battery cover, install the batteries, close the battery cover and then hang it on the tree. While on the tree they only light up or make a sound if you push a button. They do not offer continuous light. After Christmas you have to remove the batteries before storing the ornament. I enjoy these ornaments, but I think Hallmark could improve them. See my comments later.
The Legacy Cord allowed the use of the plug-in ornaments without having to remove a light bulb. The Legacy Cord could only accommodate 4 ornaments, and the AC adapter that came with the Legacy Cord was the heaviest AC adapter I have ever encountered.

The demand for Legacy Cords is very high (check prices on ebay). Hopefully, Hallmark will reintroduce this product.
I feel that the Magic Cord was a huge step forward. It allows a low level of synchronization between ornaments. And, by connecting 3 Magic Cords together you can have 17 ornaments connected to each other.
The Keepsake Power Cord was another huge step forward. The cord itself is very lightweight and flexible. And, it does not require each ornament have a cord dangling from the back. The Keepsake Power Cord is like an octopus with fairly long wires that have connectors that plug into the ornament. Along with the Keepsake Power Cord, Hallmark has introduced Storyteller ornaments. These ornaments plug into the Keepsake Power Cord for power, but they communicate wirelessly with each. In a series (say the Peanuts Storytellers), they communicate with each other, they light up when they speak, and they are aware of which other Peanuts Storyteller ornaments are present. There are other ornaments that use the Keepsake Power Cord strictly as a power source.
I would really like to see Hallmark discontinue battery-powered ornaments and have those ornaments connect to the Keepsake Power Cord. This change would eliminate the need to install and uninstall batteries. The ornaments could light up continuously and look nicer on the tree. Hallmark could avoid the need to supply batteries with ornaments.
3 of our trees only have battery-powered magic ornaments, but across the other 6 trees, we use 10 Legacy Cords, 10 Magic Cords, and 12 Keepsake Power Cords. Using these cords does require some planning on how/where to install them.
If you have read this far, thanks for sticking with me.
I would appreciate your comments.