Structural isomerism

Structural isomerism is a form of isomerism whereby the atoms are bonded together in a different order in each isomer (as opposed to stereoisomerism.)

Chain isomerism

Different isomers in this group have a varying degree of branching on their hyrocarbon chain.

Position isomerism

This is where a functional group changes position along the chain.

Functional group isomerism

This is where a functional group splits up and becomes a different group.