Cut and pasted this from info obtained in the internet. Nothing is clear cut. There are many crossovers. I think my daughter has both ecto and meso.
Ectomorph
An ectomorph is an individual who is small framed and has extreme difficulty in gaining weight. In this case the metabolism is very fast. The ectomorph recovers from training quite fast (given proper nutrition), allowing for slightly more frequent training bouts. Total fat deposits are usually low. More calories must be ingested by the ectomorph than those in either of the other two metabolic categories. Ectomorph can only capitalize on their ability to recover more quickly from exercise by ingesting more total calories. If too few calories are present, the muscles will eat away at themselves for recovery energy and the ectomorph will remain just that...an ectomorph.
Mesomorph
A Mesomorph is individual who has little problem with fluctuating body weight, the metabolism is considered normal, and his/her frame size is average. The Mesomorph usually appear larger, stronger, and healthier than the ectomorph with slightly greater bodyfat levels. The Mesomorph requires fewer calories per pound of lean weight to maintain muscle tissue than does the ectomorph and therefore suffers less muscle tissue breakdown. The Mesomorph, having a somewhat slower metabolism, does not recover quite as quickly from exercise as does the ectomorph. For this reason, the Mesomorph requires slightly longer between workout and recovery periods.
Endomorph
The endomorph is usually heavy set, has a relatively slow metabolism, and is considered large framed. The breakdown of lean muscle tissue does not occur as readily as in the other two categories. The endomorph also requires fewer total calories to maintain lean weight than the other two metabolic types. Recovery periods between heavy training bouts should be longer since the endomorph has a slower metabolism. Endomorphs are not to be confused with those who are overweight due to over consumption. The true endomorph usually consumes fewer calories.