I suspect that "methods" were originally distinguished from "subroutines" because it made the rain-dance about the new cure for all civilisation's ills and the heartbreak of psoriasis, Object-Oriented Programming, look more impressive. After one has seen a few programming religions launched, the similarities blur the differences. Profundity through obscurity always helps the marketing, because it slows the recognition.
Subroutines are blocks of code that can be used anywhere within a scope that may be global or local. Methods are a subset of subroutines that can only be used within a particular scope on particular kinds of things.
