Lynn, Lucy, Maria, and BurghGal,
Thanks for taking a look. These train pieces that are actually made to be run outside, but they're so large, they're eye-popping around a Christmas tree. They're "Large Scale," sometimes called "G Gauge," a scale that has been popularized since about 1970 by LGB. I have a whole website dedicated to outdoor trains here: https://familygardentrains.com/
Specifically, the track, the passenger car, and the power supply were made by AristoCraft, a company that the recession put out of business. But they were very popular and pieces are still available. I chose the car because I like seeing lighted passenger cars. I have other ones, but they're still buried since the move . . .
The locomotive was made by Lionel when it tried to get into the garden train market (in the mid-1980s) and failed miserably (by the mid-1990s) because of many bad engineering and marketing decisions. This loco was the most reliable piece they made; I learned last year that it was actually designed by another manfacturer for Lionel, which explains its superior quality to the rest of that line. It has appeared many colors, but to my knowledge hasn't been made for decades. The "Large Scale" trains Lionel makes now are cheap battery-powered toys. I have a few of those that I let little kids run when they visit. Not this one.
I have this in a red-and-green Christms paint job, but I chose the most garish one I had because this one is more reliable and I wanted it to show up. No, Pennsylvania never ran any lime-green locomotives in the real world.
Sorry, more than you wanted to know. My Big Christmas Train Store site would have lots of information on what is available now: https://bigchristmastrains.com/
The short version is: On30 or O gauge (like most Lionel) for Christmas villages. O gauge or Large Scale for Christmas trees. (And as you can tell, I prefer the latter.)
Have a great 2018, all!