Trying to compare the ECW to any later war is a nightmare. It's hard enough trying to get one's head around it conceptually on its own terms. It's also hard to judge it without taking into account the benefit of hindsight.
It is relatively easy to cast the king as a tyrant determined to impose a strict divine right absolutist rule on the country. It's also easy to characterise Parliament as a bunch of power-crazed fanatics hell-bent on destroying all sources of authority in the country save themselves.
Both would have a nugget of truth; neither would tell the whole story.
The religious factor can't be underestimated. Really I think the ECWs should be considered in its context as the last phase of the European Wars of Religion.
Adding to the complication is that the common conception of king vs Parliament is misleading. While they were at odds at an institutional level, many members of Parliament (somewhere between a third and half) were royalists. I'm not 100% sure but I wouldn't be surprised if it turned out more MPs died fighting for the king than Parliament. What each side was fighting for seemed to change periodically. While Parliament might have started off claiming to fight for liberty, in some of the later wars it almost looks the other way round. The second war saw the Scottish army – the king's most implacable enemies from before the start of the first war – join his side to oppose their former allies?!
With that taken into account it's perhaps not surprising that the Parliamentary victory was a disaster for Parliament itself, and that in fairly short order it was overthrown by the forces it had arrayed for its own protection.
So, bluh. While we've done a good job of agreeing what the result of the civil war meant in retrospect (or at least we all agreed after 1688), I'm not convinced that's what was actually being fought over at the time. The politics of the era were peculiar and I think it's hard to take the ideology of either side and compare it to that of someone else in a different war, and hence trace any real consistency in sympathy between the ECW and ACW in terms of which side fires you up.
