The test is a bit more involved than a normal driving test. A normal test just involves reading street signs and how to handle things like right of way, don't pass on the right, use your blinker, basic important topics. CDL tests ask questions about maintenance (how often to inspect tires?), about how big trucks move on the road compared to little cars (which kind of truck could get stuck on a RR crossing?), and misc stuff like hazmat diamonds. It's not the hardest test in the world but it's more studying than a normal DL test.