Chain isomerism and its types.

Chain isomerism: The compounds which are having same molecular formula but differs in the number of carbons in the parent chain are called chain isomers and the phenomenon is called chain isomerism.
Ex:  ${\mathrm{C}}_4{\mathrm{H}}_{10}$

Metamerism: The compounds which are having same molecular formula but differs in alkyl groups attached to the bivalent functional group in the molecule are called metamers and the phenomenon is called as metamerism.
$\mathbf{Eg}:{\mathrm{C}}_4{\mathrm{H}}_{10}\mathrm{O}$
${\mathrm{CH}}_3-\mathrm{O}-{\mathrm{C}}_3{\mathrm{H}}_7$
methoxy propane
${\mathrm{C}}_2{\mathrm{H}}_5-\mathrm{O}-{\mathrm{C}}_2{\mathrm{H}}_5$
ethoxy ethane