Rhetorical Figure

Rhetorical Figure

Hello,
I am not sure if this is the correct place to submit this question, but... I have a question. :)
Is alliteration only when two words next to each other begin with the same letter or sound, as: “But oh! Relieve a wretched parent’s pain,” or: “And Troy’s proud walls lie level with the ground.”,
or is it when there are multiple words (not necessarily next to each other) that begin with the same letter/sound? As: “And hissing fly the feather’d fates below.” or: “Or fed the flames with fat of oxen slain;”?

Thank you so much for your time!
-Miriam