Quartz benchtops are made from loose quartz that is blended together with pigment and binder, and accordingly are referred to as “engineered” benchtops because they are not entirely natural (although loose quartz does make up over 90% of quartz benchtops).
Quartzite benchtops, on the other hand, are entirely natural and are mined and then sawn into benchtop-sized slabs.
Quartzite is created when sandstone undergoes extreme pressure and heat in the crust of the earth due to tectonic plate compression.
With respect to their appearance, it is hard to say simply if one or the other is more beautiful since this is a matter of taste. Generally speaking, however, if you tend to prefer more natural looking colours and patterns, then you will probably prefer a quartzite benchtop. Or, if you care less about naturalness and want to have a wider range of colours and patterns to choose from, then you will probably be better off with a quartz benchtop.
Though quartzite does naturally occur in a fairly wide range of colours (white, grey, pink, red, yellow, blue, and green are all common), with quartz there is really no limit when it comes to colour as pigment can be added into it.
As for longevity and durability, quartzite is definitely harder (it is even harder than granite), although quartz is by no means fragile. Quartzite also withstands heat much better than quartz, since the resin in the latter is a type of plastic and can melt if subjected to temperatures above 300 degrees Fahrenheit.
One advantage to quartz, on the other hand, is that because it is more flexible than quartzite it is much less likely to be chipped or dented. Both surfaces can be scratched by a sharp knife so cutting boards are recommended for either one.
Regarding maintenance and cleanup, quartz is the winner as it is very easy to clean up just by wiping it with a damp cloth. You don’t need to worry about it absorbing moisture or stains and there is no need to have it sealed or treated regularly.
Quartzite, on the other hand, because it is a natural piece of stone is porous and will absorb liquids or other spills if it is not sealed properly and regularly. When it is properly sealed, however, quartzite is also very easy to clean (so the disadvantage in comparison with quartz is simply that you will need to have it resealed periodically, typically once or twice per year).
Finally, with respect to the price, in most cases the cost of benchtops in these two materials will be very similar (both begin at around $60 per square foot, though the average cost of both will normally be over $100 per square foot), so price is not really an issue when it comes to choosing between quartz and quartzite.
Unless, however, you have some kind of irregular or complex design in mind for your benchtop. If you require a specialized cutting job then quartzite will likely cost you more money as it requires much more care and skill to saw your benchtop out of a pre-existing piece of stone. With quartz, on the other hand, an irregular shape is much more simple as loose quartz and other materials can simply be poured into a mould made with whatever dimensions you like.
In conclusion, though there are some differences with respect to appearance, durability, maintenance, and cost, in most cases none of these differences will be extremely dramatic, meaning that both quartz and quartzite are highly beautiful as well as highly durable materials for your kitchen or bathroom benchtops.