Definition of dray. : a vehicle used to haul goods; especially : a strong cart or wagon without sides.
Expressions versus Equations. A difference between expressions and equations is what each represents. An expression shows a math relationship. One key to an expression is that there is no solution. An expression does not have an answer. An expression, however, can be evaluated. To evaluate an expression, substitute values for the variables.
A word equation represents the ingredients of the reaction. The reactants and products are written in words. The '+' symbol shows the separate ingredients, while the ' ' symbol stands for 'reacts to form'. Chemical equations go a bit further by being more specific about the formulae involved.