Definition of dray. : a vehicle used to haul goods; especially : a strong cart or wagon without sides.
The main difference between an equation and a function is the fact that an equation usually deals with a single input, whereas, a function can have numerous inputs. In mathematics, an equation is used to denote the equality between two expressions.
Difference between identity and equation. An identity is true for any value of the variable, but an equation is not. For example the equation is true only when x=4, so it is an equation, but not an identity. In fact, when we see an equation like that, we are usually trying to solve it. That is, find the single value of x that makes the equation true.