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There are two ways concentrated solar power is used that highlight it's differences.
In the first case, like the panels being sold by MicroPV, to name one of about ten vendors, sunlight is concentrated onto a normal PV cell. This makes the unit cheaper because mirrors/lenses are cheaper than solar cells. It's making the solar cell do more. There are also PV cells specially made for this purpose, and with those, concentrating the sunlight not only allows a smaller cell to produce more power, but it also turns more light per square meter into electricity because these special cells get more efficient when there is a higher concentration of light.
The advantages of using PV are ease of maintenence and the fact that eventually solar cells may surpass the theoretical limit of alternative methods in terms of energy efficiency, making the solar plants more compact.
In the second case we pass entirely on using a PV cell. Instead the sunlight is turned to heat, and the heat is turned to electricity. These systems are called "solar thermoelectric" instead of "photovoltaic" because they don't convert the light directly, though one of the varieties of "solar thermoelectric" power is called "thermophotovoltaic" for reasons below. Usually these types of installations are big, and there are a variety of forms they can take from "solar chimeys" to trough farms, to dish arrays.
There are two main advantages to this approach. One is that you can merge the solar heat with heat from other sources before you run it through the generator -- that can help make the solar installation more reliable and capable of handling load peaks on cloudy days. The other is that the heat energy can be stored for later use, perhaps discharged during the night when the air is cooler (which means you'll get more electricity from it -- it's the difference in temperature between your cool side and hot side that matters, not the absolute temperature.)
How the heat gets converted to electricity is a matter of choice. (In fact in some cases you may convert it into something other than electricity, like air conditioning.)
You can go for a solid-state or near-solid state solution like thermopiles, which are microchips that generate electricity when you heat one side (and cool the other) or a thermacoustic heat engine which is a specially shaped bottle full of gas with a set of "channels" inside it that causes the gas to vibrate, driving a coil for a magnetic pickup, the only moving part (which doesn't actually move much.) Both of those options are still in the "promising, but not quite there yet" category, though there have been some very exciting discoveries in the field of thermopiles lately.
You can also go for a traditional gas heat engine like a stirling engine/free piston stirling, or a steam/rankin/ammonia setup, etc. The stirlings can be pretty small (some have even been mounted right on the concentrator dish) whereas the other technologies usually are used in big installations where many dishes or troughs feed a central generator. Power companies like doing it this way because they already have the engineers on-staff to handle the heat engines -- they are more used to this approach.
Solar chimneys are their own animal -- they capture the heat, turn it to wind, and turn the wind to electricity. That may seem a bit round-about, but they are actually a good idea because they get some more power out of the system by reaching up into the sky to take advantage of heat and pressure diferentials at the top of the chimney.
Finally there's the "thermophotovoltaics" I mentioned. These are special PV cells tuned to a specific high-infrared frequency. They are very efficient, but only at that frequency, so they wouldn't produce much power when exposed to sunlight which has a lot of frequencies in it. The solar heat is concentrated onto a peice of material that, when it gets hot "glows" at the same frequency that the PV cell is tuned to. So these systems are sort of an "input transformer" for sunlight, changing sunlight to a special form of light via a heat step, and then to electricity. These are the dark horse technology that not many people realize is out there -- they already have demonstrated efficiencies close to the most efficient stirling engine setups and the most efficient high-concentration PV cells.
And I think that about covers it.
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