A flue liner has to be able to stand up to the stresses and strains of being pulled and pushed down a chimney. It also needs to be impervious to continuous high temperatures and bursts of immense heat. The best brands will ensure that any moisture or tar that runs back down the liner goes straight into the stove without leaking out of the fitting whereas cheaper options might fail to do so. There are different grades of liner available, an average one used for most domestic uses but there are higher grades on the market which are more suitable for higher temperatures, possibly for industrial usage.
If you have a chimney then a chimney flue liner is what you require but if you have a stove then you are more likely to require a stove flue pipe. The chimney liner is made of a flexible material which can be fitted into any shaped chimney and then an insulator is usually poured down the sides. Conversely, a stove flue pipe is usually made up of solid pieces of tubing in standard lengths. You buy as many lengths as needed then join and seal them together to make one long flue pipe. The individual pieces come in different shapes and different diameters so they can suit your requirements.
When buying flue liners, it is important to make sure you get the correct one to achieve an efficient heating system.