I know what solar power and solar panels  are but what is the difference between mono and polycrystalline photovoltaic (pv) cells?

Rigid solar panels are made of either mono or polycrystalline silicon cells. Mono-crystalline cells are cut from a piece of silicon grown from a single crystal. Polycrystalline cells are cut from a multifaceted piece of silicon crystal. Historically, mono-crystalline cells had higher efficiencies and were considerably more expensive. However, these days there is very little difference between the two in either price or performance (as can be seen from our prices and spec sheets). Mono-crystalline photovoltaic cells still have a larger share of the market and sometimes offer a longer warranty period compared to their polycrystalline cousins.

The easiest way to identify a mono or polycrsytalline solar panel is visually: The former has a uniform appearance and the latter appears to look like shattered glass.