How is metameric segmentation different from nonmetameric segmentation?

Hope it's helpful for you.

Metameric segmentation is a type of segmentation where external division corresponds to internal division. The body is often divided both externally and internally into a number of segments e.g. annelids.

In non- metameric segmentation, ectodermally derived tissues are only involved e.g. Cestoda tapeworms.

Metamerism is found in annelids and Arthropds mainly.Due to this character their body is segmented completely.Body is like train with many compartments.
eg:Earthworm, scorpion etc
The difference between organism showing metamerism and without metamerism is the absence of segmentation of body.
eg :Mammals

In some?metameric?animals thesegmentation?is visible externally but in others external?segmentation?has been lost and internal?segmentation?is best seen in the embryo.?Non-Metameric Segmentation: ADVERTISEMENTS: ...?Segmentationcan be confined only to ectodermally derived tissue, e.g., in the Cestoda tapeworms.