I'm struggling to understand the practical difference between carbon composition resistors and metal film resistors. From what I've read, metal film resistors tend to be available in more precise tolerances than carbon composition ones. Other than that, are there any differences between the two?
Carbon composition resistors have higher noise and are prone to aging (change it's resistance with the time). Additionally they can change its resistance because of high voltage or high temperatures applied.
That is why the precision resistors with tolerance less than 1% are always made with metal film technology.
The other types of carbon resistors (carbon film resistors for example) has better properties than carbon composition resistors, but are still worse than the metal film resistors.
Metal film can be made to tighter tolerance, is more stable, and is less noisy. Nowadays there is very little reason to use a carbon composition resistor. Metal film resistors are made in such large numbers that there is no longer a cost advantage to using carbon composition.