Metamerism and position isomerism are two forms of structural isomerism, which describe the arrangement of atoms within a molecule. Although they share some similarities, there are distinct differences between these two types of isomerism.

Metamerism:
Metamerism is a type of structural isomerism where molecules have the same molecular formula but differ in the arrangement of alkyl groups on either side of a functional group. It occurs due to the presence of different alkyl groups that can be positioned on either side of the functional group. The functional group remains unchanged.

Position Isomerism:
Position isomerism is a type of structural isomerism where molecules have the same molecular formula but differ in the position of a functional group or substituent on the main carbon chain. It occurs when the functional group or substituent can be positioned at different locations on the carbon chain.

Differences between Metamerism and Position Isomerism:

1. Definition:
- Metamerism: Metamerism occurs when molecules have the same molecular formula but differ in the arrangement of alkyl groups on either side of a functional group.
- Position Isomerism: Position isomerism occurs when molecules have the same molecular formula but differ in the position of a functional group or substituent on the main carbon chain.

2. Cause of Isomerism:
- Metamerism: Metamerism is caused by the presence of different alkyl groups on either side of a functional group.
- Position Isomerism: Position isomerism is caused by the different positions of a functional group or substituent on the carbon chain.

3. Functional Group:
- Metamerism: In metamerism, the functional group remains the same.
- Position Isomerism: In position isomerism, the functional group may change position.

4. Examples:
- Metamerism: An example of metamerism is seen in the isomers of butanol, where the alkyl group can be positioned on either side of the hydroxyl group.
- Position Isomerism: An example of position isomerism is seen in the isomers of butene, where the double bond can be positioned at different locations on the carbon chain.

5. Effect on Chemical Properties:
- Metamerism: Metamers have different physical and chemical properties due to the presence of different alkyl groups.
- Position Isomerism: Position isomers may have different physical and chemical properties depending on the position of the functional group or substituent.

In summary, metamerism and position isomerism are both forms of structural isomerism, but they differ in the arrangement of alkyl groups and functional groups/substituents, respectively. Metamerism is based on the arrangement of alkyl groups on either side of a functional group, while position isomerism is based on the position of a functional group or substituent on the carbon chain.