Would you like a small Thomas the Tank Engine for your child, one whose track will fit on a board under your child's bed? I consider N scale the smallest practical scale to give a child. These Thomas trains may be large enough for children to handle, and their size allows your child more track in smaller spaces. American manufacturers seem to think American kids have ample pace to lay out model train tracks. Japanese manufacturers take a more realistic view. This is why the N scale Thomas and Friends models are made only by the Japanese manufacturer Tomix.
Thomas, engine No. 1, is an 0-6-0 switcher tank engine. Thomas is available in either a Tomix starter set with an oval of track, a power pack, Troublesome Truck, Foolish Freight Car; or in a set with the small, Annie and Clarable old fashioned coach cars, but without track and powerpack. (Annie and Clarable have faces, of course) If you are starting your child out with electric trains, I'd recommend buying the Thomas, Annie, and Clarable set and getting a Kato Unitrack starter set. As your child will certainly want more track over time, you'll find Kato track far easier to acquire in North America.
Henry the big green No. 3 engine is a 4-6-0 steam engine. He comes with a six-wheel tender permanently attached by a drawbar and one large modern Red Express Coach car (with no face). Additional Red Express Coach cars are available in two-packs.
James, the bright red 2-6-0 steamer is engine No. 5 engine. He also comes with a six-wheel tender and Troublesome Truck & Foolish Freight Car. James may be the least suitable of these toys for a young child because his tender isn't permanently attached and the way the drawbar is keyed may make it difficult for a child to attach.
Little, green 0-4-0 Percy is engine No. 6; another switcher even smaller than Thomas. Percy comes with a Sodor Mail Car (no face). Additional Sodor Mail Cars are available in two-packs.