Photovoltaic is a type of solar panel that produces electricity from sunlight, usually converting about 5% - 22% of the energy received from the sun into usuable energy. There are different types including those grown in a lab, silicone, and glass. Another type of solar panel is solar thermal which convert sunlight into heat. This is usually ran into some sort of system that heats water or a mixture w/ glycol in colder regions. This hot water can be used for showers, etc, or heating the home. You get much more bang for your buck with solar thermal.
Both of them are different types of solar panel. EDIT: Misspelling on Jeff's answer below! I think he means 'silicon,' not 'silicone!' Solar cells are typically grown on a glass substrate or put onto glass. Silicon is currently the most common material, followed by CdTe or cadmium telluride. Other materials like CIGS (Copper Indium Gallium (di)Selenide) are breaking into the market. Some people have great hopes for organic or 'dye' solar cells.
Dear friend, Photovoltaic Panels and Solar Panels are the same products.
Solar panels collect energy from the sun and then provide it to a system that typically concentrates it. Solar energy comes to us in the form of heat and light. Photovoltaic panels take the light energy from the sun and convert it to electricity. Although the maximum efficiency is around 42% in the lab most commercial models you will see are from 8 to 22% efficient. Adding collectors together concentrates this energy into usable amounts. Solar thermal panels are from 60 to 80% efficient. They come in many different types and collect the heat energy from the sun. That heat may then be stored in some form of thermal mass where it becomes concentrated sufficiently to be used. Solar thermal panels can be used to heat a medium. This can be a phase change material, air, or water. Solar thermal air panels are cheap to make and offer a quick pay back period. Solar thermal panels for some heating and hot water systems circulate water. Vacuum tube collectors are solar thermal panels that may heat water directly or a phase change materials. They can operate better in cloudy and colder weather with more efficiency. Air and water panels are often called flat panels as a way to contrast them with vacuum tube collectors. Solar thermal panels often lead to some form of energy storage called thermal mass (water tanks, phase change materials, masonry walls and rocks.) Photovoltaic panels make electricity that is stored in batteries, used or sent to the general grid. Panels are only one way to collect solar thermal energy. Other types of collectors are used commercially and are often called simply solar concentrators. Some are called parabolic trough collectors and parabolic dish collectors.
