They are different in structure as one serves in an open system (lymphatic system) while the other serves is closed system (circulatory system).
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*This question is common, so this answer I use a lot. I copied my own work.*
The name that is given to cell division in prokaryotes is C) Binary Fission.
E Coli bacterium are about 2.0 micrometers in length and .25 to 1 micrometer in diameter. In comparison, a red blood cell is about 6 to 8 micrometers in diameter and a thickness that ranges from .8 to 1 micrometer in the center to 2 to 2.5 micrometers at the thickest point.
Answer:
Because of evolutionary traits based on the environment.
Explanation: This is probably because they live in a similar environment, so they both evolved to have similar adaptations to make them excel in that specific enviroment