Metamerism is one kind of structural isomerism which arises due to the unequal distribution of carbon atoms on either side of the functional group or different alkyl groups attached to the either side of the same functional group and having the same molecular formula.
e.g., C4H10O:
(i) CH3-O-CH2-CH2-CH3
I-methoxypropane
(ii)
2-methoxypropane
(iii) CH3-CH2-O-CH2-CH3
Ethoxyetyhane