Explanation:
Difference between the two:
Molecules of elements are defined as the substances which are made up of similar type of atoms. For Example: [tex]Cl_2[/tex] etc..
Molecules of compounds are defined as the substances which are made up of different type of atoms. For Example: [tex]H_2O[/tex] etc..
Similarity between the two:
These two substances are known as pure substances. A pure substance is defined as the substance which is formed by same or different type of atoms which are chemically combined in a fixed ratio by mass. Compounds and elements are considered as pure substances.