The BEP principle says that for analogous reactions, enthalpy change and activation energy are linearly related. What is meant by analogous reactions?

Eg. For electrophilic addition of HBr to pent-1-ene, two products (2 or 1-bromopentane) are possible. But carbocation for formation of 2-bromo-pentane is more stable, so 2-bromopentane is also more stable than 1-bromopentane. Here, BEP applies.

But then for E2 elimination of HBr from 2-bromobutane, the transition state leading to formation of but-1-ene is more stable than that for formation of but-2-ene, although the product but-1-ene itself is less stable. Here, it seems to contradict BEP principle? Are these not considered analogous reactions? If so, why?

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    $\begingroup$ The 'analogous' would refer to, for example, HBr + pent-1-ene and the analogous reaction HBr + hex-1-ene. These two analogous reactions are in the same family of reactions, HBr addition to alkenes. $\endgroup$ Sep 16 at 14:39

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