As Ed1 and the others have said, you have to read the description carefully of a listed uke.
"All Koa" usually means it is a laminate body with a thin outer layer of koa wood for looks. (Or other fancy-looking woods.) Many laminate ukes sound rather boxy and dull. But there are some gems out there. One advantage of laminate is that it is strong and not as susceptible to shrinkage and swelling due to large changes in humidity and temperature.
"Solid Koa Top and All Koa Body." Means only the top (soundboard) of the uke is made of solid Koa wood. Usually, two pieces of spruce joined together in a bookend (mirror image) fashion. The koa in the back and sides is the top layer of a laminate. Usually, sounds better than an all-laminate body with better projection and a fuller sound. But not always.
"Solid Koa" or "Solid Spruce Top, with Solid Koa body." Means the top is made of solid koa or spruce wood. Usually one or two pieces. The back and sides are made of solid koa wood. Usually two pieces for the back and two for the sides. But a few higher end sopranos are made with one-piece top, back and sides.
There is some discussion about whether bamboo ukuleles are solid or technically a laminate. While all-bamboo, the pieces than make up the planks are strips of bamboo in a resin. The makers tend to call the ukes: "All Solid Bamboo."
Necks are usually make of a solid wood. The most common is mahogany. Some are carved from one piece. Others have heels (the part of the neck that joins to the body) that is made of 3 pieces of solid wood glued together and then shaped.
The following are decorative accents added to a ukulele often referred to as "bling." They do not affect the sound of a ukulele at all. They are for aesthetic purposes only. Some inexpensive ukes have a lot of bling and look impressive, but don't sound very good:
"Binding" is an edge around the top and possibly the back that is both decorative and helps protect the edges of the body. It can be made of wood, or a man-made material.
"Purfling" is very thin strips of material added for decoration around the edges, of the body, rosette and other parts of a uke.
"Rosette" a decorative design around the soundhole.
You can find ukulele reviews, playing tips and a lot of information expressly written for new and beginners at:
www.gotaukulele.com
I wish I had found it earlier when I was just starting out. I would have bought a different first ukulele.
Oh, one other thing: you'll see "setup" or "action" mentioned a lot on the Forum. Mostly, it means the height of the strings from the top of the 1st fret and the 12th fret to the bottom of the strings. A good setup lowers the height to make playing much easier. Especially for barre chords. Most quality online ukulele stores include a setup in the cost. Other places, such as Amazon do not even open the box. They sell whatever the maker sent them. As is. There are a handful of ukes that come from the factory setup with an OK average height.
Hope this helps. Have fun.