The terms are pretty close together in meaning. Here is what my local dictionary says about them:
ideology — a system of ideas and ideals, esp. one that forms the basis of economic or political theory and policy
worldview — a particular philosophy of life or conception of the world
The easiest way to distinguish between the two is to note that ideology is more proactive. An ideology will dictate what your actions or policies are. A worldview is more of a perspective or explanation of the way things are:
A common worldview suggests that all human life is valuable.
Christian ideologies dictate that one should do unto others as you wish them to do unto you.
The terms can crossover depending on how one is expressing the philosophies:
My worldview claims that one should eat cake every day.
Here the worldview is making a claim that a certain action should take place but the focus is not on actually doing that action. Following through on those actions would essentially be adopting them into your ideology:
I eat cake every day. It is part of my ideology.
Naturally, this causes a lot of confusion and most of the time you can get away with using either term. Here are my rules of thumb:
- Is the philosophy suggesting a course of action? If not, use worldview.
- Is the suggested action required to self-identify as belonging to that philosophy? If not, use worldview.
- Otherwise, use ideology.
Examples of all three cases:
In my worldview, cake is in its own food group.
I am a cakatarian; this worldview claims that cake should be eaten with every meal.
I am an anti-cakatarian; my ideology prohibits eating any cake.
The distinction between the last two examples is probably me shoehorning a difference into the words that doesn't actually exist but I find it helpful when I need to distinguish between them. The real key difference is that of action/inaction. This unfortunately presents us with a rather large gray area.
When in doubt, look at the group in question and see how they describe themselves. Religious groups tend to have worldviews; political groups tend to have ideologies.