So I've written an example in a comment here https://news.ycombinator.com/item?id=32507364 , but to try to emphasize the difference between waterfall and, um, non-waterfall is that historically (as far as I know) the scope was fixed in waterfall (and releases just got delayed more and more), whereas agile (based on "extreme programming" right?) says the opposite. Release often, in time-fixed increments, and try to always release something working that slowly but surely approximates the end goal.
This of course implies that there's an end goal (so it's not surprising that there's a rough plan with so and so many milestones already laid out), but allows for moving that goal. Of course, as I vehemently argued in that comment, doing this by force in a top-to-bottom way, spending more time chasing this constantly moving end goal in planning session, than actually working on delivering something is a folly.
(Of course there are very turbulent situations where a small company/group fights for its own survival, pivots every second week to something else, throws out half of the existing stack every quarter, etc.. etc... but in that case the problem is not with "agile". The problem is trying to do something that has clearly no market traction without sufficient money and a sane business plan.)
This of course implies that there's an end goal (so it's not surprising that there's a rough plan with so and so many milestones already laid out), but allows for moving that goal. Of course, as I vehemently argued in that comment, doing this by force in a top-to-bottom way, spending more time chasing this constantly moving end goal in planning session, than actually working on delivering something is a folly.
(Of course there are very turbulent situations where a small company/group fights for its own survival, pivots every second week to something else, throws out half of the existing stack every quarter, etc.. etc... but in that case the problem is not with "agile". The problem is trying to do something that has clearly no market traction without sufficient money and a sane business plan.)