Conventional sources of energy refer to traditional forms of energy production such as coal, oil and natural gas. These sources are widely used and have been in use for many years. They are also known as fossil fuels as they are formed from the remains of plants and animals that lived millions of years ago.
Non-conventional sources of energy on the other hand refer to alternative forms of energy production such as solar, wind and hydropower. These sources are considered to be renewable as they do not deplete over time. They are also considered to be more environmentally friendly as they do not produce harmful emissions like conventional sources do.
In summary conventional sources of energy are traditional and widely used but have negative environmental impacts while non-conventional sources are alternative and more environmentally friendly but are not as widely used.