Dry climates are climates where the precipitation is very low, and it appears just on few occasions in the year, occasionally not appearing at all in multiple years, while the tropical climates have high precipitation rates, some have throughout all of the year, some seasonally, but in each case it is a large amount of rainfall.
The temperatures in the dry climates can either be extremely high for the whole year (like the hot deserts, 50 C degrees +), or have very hot summers and very cold winters (like the cold deserts, 35 degrees + to -40 C degrees). The tropical climates mainly have the tendency of having constant temperatures throughout the year, or with small variations, and they are mostly in the range between 24-30 C degrees.
The dry climates are located as a belt just south and north of the tropical climates, as well as deep into the mainlands, like in Central Asia for example. The tropical climates are located on and around the Equator.