10x is literally the difference of an order of magnitude.
An order of magnitude is an exponential change of plus or minus 1 in the
value of a quantity or unit. The term is generally used in conjunction with
power-of-10 scientific notation.
Order of magnitude is used to make the size of numbers and measurements of
things more intuitive and understandable. It is generally used to provide
approximate comparisons between two numbers. For example, if the
circumference of the Sun is compared with the circumference of the Earth,
the Sun's circumference would be described as many orders of magnitude
larger than the Earth's. [1]
An order of magnitude is an approximation of the logarithm of a value relative to some
contextually understood reference value, usually 10, interpreted as the base of the
logarithm and the representative of values of magnitude one. [2]
Yes, an order of magnitude literally means 10x. But in my experience, in common speech it's often used to convey an approximation. i.e. 'Changing this will decrease performance of that endpoint by an order of magnitude', when it's really somewhere around 10x. If someone said 'decrease performance by 10x' that seems much more concrete to me.