Low aprox. 40C - High 60-65C (on Vented, and up to 70C on Condensors), depending on Manufacturers. Some models such as Miele, and Hotpoint offer allergy/hygiene cycles which can go up to 75C (usually 70C and held for a high period).
Low is equivalent to a perm press/half heat cycle in USA.
Low heat will take longer to dry, but doesn't nessecarily use less energy.
I always use high heat as it dries fastest (and the fact my Dryer has only High heat, except for a delicate cycle, and a cycle called Bed+Bath which mixes the heat throughout the cycle).
I am sure in the US High & low heat options are available on most manufacturers?? in fact when I went to USA a top load matching Whirlpool dryer (electric vented) had low & high heat, just around the timer dial instead of buttons.