Customers that are new to business radios are confronted a several confusing options, one of which is the type of frequency to choose: UHF or VHF. These abbreviations make no sense to most people and without some research it is easy to choose a radio that is not right for your situation.
The quick answer is: choose VHF if you plan to only use the radios outdoors and in an area that is relatively free of obstructions, such as buildings. If you plan on using the radio indoors, both indoors and out, or outdoors but around buildings, choose UHF. UHF is the better all around signal and is by far the most popular, so if you are in doubt, choose UHF.
UHF signals don't travel quite as far outdoors as VHF signals, but they do a better job of penetrating wood, steel, and concrete, giving you better range and performance in urban environments and around buildings. VHF signals travel farther, absent obstructions, and tend to "hug" the earth better, providing better performance outdoors or in hilly terrain.
Buyer's Guide - VHF Business Radios
Buyer's Guide - UHF Business Radios
Two Way Radio Basics
MURS: Unlicensed VHF
Radio Compatibility: Which Models Will Work Together
The Two Way Radio Show TWRS-02 - An Introduction to Business Radios
Radio 101 - The difference between UHF and VHF radios