(a) Term — 

Elements – Pure substance made up of one kind of atoms only. e.g. Iron [Fe], Sulphur [S] 

Compounds – Pure substance made up of two or more different elements, e.g. Iron sulphide [FeS] 

Mixtures – Impure substance made up of two or more elements or compounds, e.g. Iron and sulphur mixture. 

(b) Existence — 

Elements – Elements i.e. atoms are present on their own. e.g. Iron and sulphur exist on their own as elements iron and sulphur. 

Compounds – Components in a compound present in a definite proportion. e.g. Iron and sulphur are chemically combined in a fixed ratio in iron sulphide. 

Mixtures – Components in a mixture present in any proportion. e.g. Iron and sulphur are mixed in any ratio in the mixture of iron and sulphur. 

(c) Properties — 

Elements – Elements have a definite set of properties. Elements classified into metal and non-metals each with its own properties. 

Compounds – Compounds have a definite set of properties. Elements of a compound do not retain their original properties. 

Mixtures – Mixture not have a definite set of properties. Components of a mixture do retain their original properties. 

(iv) Separation of compound — 

Elements – Elements occur on their own or as compounds and can be separated by chemical and physical methods. Example : Iron, copper. 

Compounds – Elements in a compound are chemically combined and can be separated by chemical methods only. Example : Iron Sulphide, copper oxide. 

Mixtures – Components in a mixture can be separated by physical methods only. Example : Iron + sulphur