Not sure what output you want to see. But... Select column C.
data/Data Tools/Text to Columns/Finish
Then in M2, an array formula (in my version of Excel, anyway!!):
=MAX(IF($E$2:$E$14=E2,$C$2:$C$14)-MIN(IF($E$2:$E$14=E2,$C$2:$C$14)))
copied down.
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