Christine -- Addison has added one bit to Boileau, and may have
neglected a connotation. The phrase "sentiroit son Rheteur" could
mean "savours of the rhetorician" (but there's no epigrammatist in
sight). Or it could mean "smacks of his rhetoric teacher." That
incorporates the possessive pronoun "son," which the other translation
ignores. In other words, Boileau suggests that exact comparisons are
pedantic. (Speaking of the bad effects of academic instruction
in writing, again....)
The other passage stresses the pleasurable effects of comparisons,
again offering a contrast with pedantic uses of rhetoric. Boileau is
more down on teachers than Addison is.
Hope this is of some use.