There are 3 main standards of euro cylinder available today. Basic 5 or 6 pin cylinders with little or no protection against the main threats which are snapping, drilling, bumping, plug-pull and picking. The basic (cheap) versions are generally poorer quality.
Then there are 1-star British standard kitemarked euro cylinders which offer protection from picking, drilling and may have sacrificial snapping points but does NOT protect against snapping. Then there are the 3-star high-security euro cylinders which offer protection against snapping, bumping, drilling, picking and plug pulling.
These cylinders offer the highest levels of protection. You can also add additional features to euro cylinders such as keyed alike (1 key operates all locks), Master keyed system, often used commercially in schools, businesses and hotels etc. This is where there will be 1 key that opens every lock in the building but individual keys only open their allocated doors.
These lock types are found on euro mortice locks for wooden doors, UPVC door, Aluminium doors, composite doors and garage doors.