The comparisons.
The traditional power supply (some call them "linear" supplies) are the old-time type and the most common. You'll usually see them in audio equipment and nearly any "wall-wart" battery eliminator. They consist basically of a power transformer to convert the line voltage up or down (or both) to suit the need, a rectifier, a filter and, optionally, a voltage regulator. The advantages of these types of supplies are simplicity, low maintanance, high reliability and low radiated RF. The disadvantages are that they're heavier, more costly for high-current versions, less efficient and take up more space.
The switch mode power supply (SMPS or switcher) is used in most computers and modern televisions. Most high-end oscilloscopes made by Tektronix since 1972 use switchers and low or high end scopes made by them since 1990 use switchers. They consist of a rectifier/filter, an "oscillator" (the switcher) that operates at a frequency of 10KHz to 1MHz), power transformer, rectifier and filter. Because of the high switching frequency, a much smaller power transformer is required since higher frequencies don't need the large cores needed by the 60Hz "linear" supplies. Also, filter components are smaller in value because the RC values for 10KHz and up are smaller than those for 60Hz. Because of the smaller components and the high switching frequency, the advantages are smaller size, lighter weight and much higher efficiency, sometimes as high as 95% compared to 60% or so for a "linear" supply. Switchers can be made with precision-wound transformers and sampling of output voltage so that it can precisely regulate the output voltage. Theyu don't often require voltage regulators at the output. This comes with some disadvantages, though. A switcher has all kinds of components sinces it's a major circuit in itself. With that is the attendant reliability problems associated with all those complex parts. Also, a switcher produces a lot of radio frequency noise that must be filtered out so that it doesn't interfere with radio and television reception. It's for this reason that you won't see switchers in sensitive radio receivers such as ham radio or short wave listening receivers.
Dean