What are the differences between reagents and reactants?

Reactants 

• Used as starting material
• Starting material undergo changes during a chemical reaction
• Are a necessity in chemical reactions
• Are essentially single compounds
• Get consumed in chemical reactions – the existing chemical bonds in the reactant compound break and form new bonds, resulting in a new compound.

Reagents

• Are substances that are added to facilitate a chemical reaction
• Have a specific function in the reaction
• Are not necessarily consumed in the chemical reaction
• May be single chemical compounds or a mixture of multiple chemical compounds
• Used for observing, examining, or measuring the extent of a chemical reaction or to identify certain functional groups
• Are not necessary for a chemical reaction to occur