What measures unit measures length or distance?

Answer 1

I assume you are asking which units of measure. Length and distance are arithmetically the same, though differ in meaning, so then you would use the units appropriate to the scale of what you are measuring, for either purpose.

So for very small lengths: inch or millimetre.

Larger sizes - perhaps the foot or yard / metres. (The centimetre is in common use for, e.g., clothes sizes, but is not one of the SI system's "Preferred units" and is not used in science and engineering, with a very few exceptions.)

Travel and land-measurement scales: yards / metres, and miles / kilometres. The Nautical Mile for marine and air navigation, because it is related to longitude and is the basis of the Knot (kt) speed unit.

Curiously the railways in Britain, where the Statute Mile and Yard remain the only legal road and railway distance units in a mainly-metric country, still use the Chain (22yd) and Yard, particularly I think for curve radii and tunnel lengths.

Those spellings ending in "tre" are correct - they are the French names, of units that were invented in France.

I have seen this type of question muddled up with an algebraic technique called Dimensional Analysis, so will note it here. It is NOT for unit conversions, but is for testing the construction of complicated multi-dimensional formulae and calculations. In it, "length" is simply physical extent or distance, so length, width and height are all just "Lengths". "Dimension" in this context does have the everyday meaning as on a workshop drawing, but is the type of measured variable, so for example [Speed = Distance / Time] has 2 dimensions: length and time.

Answer 2

Either. Length is just the distance from one end to the other.